JP2013084900A - Group iii nitride composite substrate - Google Patents

Group iii nitride composite substrate Download PDF

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JP2013084900A
JP2013084900A JP2012135772A JP2012135772A JP2013084900A JP 2013084900 A JP2013084900 A JP 2013084900A JP 2012135772 A JP2012135772 A JP 2012135772A JP 2012135772 A JP2012135772 A JP 2012135772A JP 2013084900 A JP2013084900 A JP 2013084900A
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oxide film
group iii
iii nitride
film
substrate
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Kazunari Sato
一成 佐藤
Hiroki Seki
裕紀 関
Akihiro Yago
昭広 八郷
Yoshiyuki Yamamoto
喜之 山本
Hideki Matsubara
秀樹 松原
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Sumitomo Electric Industries Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a group III nitride composite substrate having high bond strength between a support substrate and an oxide film and high bond strength between the oxide film and a group III nitride layer.SOLUTION: A group III nitride composite substrate 1 includes a support substrate 10, an oxide film 20, and a group III nitride layer 30a. The support substrate 10 is formed of polycrystalline. The group III nitride layer 30a is formed of group III nitride crystal orientated at least in a C-axis direction. The oxide film 20 is doped with impurities, a concentration of which varies in a thickness direction from a first principal plane 20s on the support substrate 10 side to a second principal plane 20t on the group III nitride layer 30a side in the oxide film 20, and is higher in the first principal plane 20s than in the second principal plane 20t.

Description

本発明は、支持基板と酸化物膜とＩＩＩ族窒化物層とを含み、これらの接合強度が高いＩＩＩ族窒化物複合基板に関する。   The present invention relates to a group III nitride composite substrate that includes a support substrate, an oxide film, and a group III nitride layer, and has high bonding strength.

光デバイス、電子デバイスなどの半導体デバイスに用いられる複合基板の作製方法に関して、特開２００７−２０１４２９号公報（特許文献１）および特開２００７−２０１４３０号公報（特許文献２）は、支持基板と半導体材料の活性層との間に介在させた少なくとも１つの薄い絶縁層を備える複合基板の作製方法を開示する。   Regarding a method for manufacturing a composite substrate used for a semiconductor device such as an optical device or an electronic device, Japanese Unexamined Patent Application Publication No. 2007-201429 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2007-201430 (Patent Document 2) describe a support substrate and a semiconductor. Disclosed is a method for making a composite substrate comprising at least one thin insulating layer interposed between an active layer of material.

特開２００７−２０１４２９号公報JP 2007-201429 A 特開２００７−２０１４３０号公報JP 2007-201430 A

特開２００７−２０１４２９号公報（特許文献１）および特開２００７−２０１４３０号公報（特許文献２）に開示された方法で作製された複合基板は、半導体材料として用いられるＳｉ（シリコン）、Ｇｅ（ゲルマニウム）、ＳｉＧｅ（シリコンゲルマニウム）、ＳｉＣ（炭化ケイ素）、ＧａＮ（窒化ガリウム）、ＧａＡｓ（ヒ化ガリウム）、ＩｎＰ（リン化インジウム）などと、絶縁層として用いられるＳｉＯ2（酸化ケイ素）、Ｓｉ3Ｎ4（窒化ケイ素）、ＴｉＯ2（二酸化チタン）、ＳｒＴｉＯ3（チタン酸ストロンチウム）などとの間の界面の接合密着性が低いため、半導体材料で形成される支持基板と絶縁層との接着強度および絶縁層と半導体材料で形成される活性層との接合強度が低いという問題点があった。 A composite substrate manufactured by the method disclosed in Japanese Patent Application Laid-Open No. 2007-201429 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2007-201430 (Patent Document 2) is made of Si (silicon), Ge (used as a semiconductor material). Germanium), SiGe (silicon germanium), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), InP (indium phosphide), etc., and SiO 2 (silicon oxide), Si used as an insulating layer 3 N 4 (silicon nitride), TiO 2 (titanium dioxide), SrTiO 3 (strontium titanate), etc., because the adhesion at the interface is low, adhesion between the support substrate formed of a semiconductor material and the insulating layer There is a problem that the strength and the bonding strength between the insulating layer and the active layer formed of a semiconductor material are low.

本発明は、上記の問題点を解決して、支持基板と酸化物膜とＩＩＩ族窒化物層とを含み、支持基板と酸化物膜との接合強度および酸化物膜とＩＩＩ族窒化物層との接合強度が高いＩＩＩ族窒化物複合基板を提供することを目的とする。   The present invention solves the above-described problems and includes a support substrate, an oxide film, and a group III nitride layer, the bonding strength between the support substrate and the oxide film, and the oxide film and the group III nitride layer. An object of the present invention is to provide a group III nitride composite substrate having a high bonding strength.

本発明にかかるＩＩＩ族窒化物複合基板は、支持基板と、支持基板上に配置されている酸化物膜と、酸化物膜上に配置されているＩＩＩ族窒化物層と、を含む。ここで、支持基板は多結晶で形成されている。また、ＩＩＩ族窒化物層は少なくともｃ軸方向に配向しているＩＩＩ族窒化物結晶で形成される。また、酸化物膜は不純物が添加され、不純物の濃度は、酸化物膜において支持基板側の第１主面からＩＩＩ族窒化物層側の第２主面にかけて膜厚方向で変化し、第１主面における不純物の濃度は第２主面における不純物の濃度よりも高い。   The group III nitride composite substrate according to the present invention includes a support substrate, an oxide film disposed on the support substrate, and a group III nitride layer disposed on the oxide film. Here, the support substrate is formed of polycrystal. The group III nitride layer is formed of group III nitride crystals oriented at least in the c-axis direction. In addition, an impurity is added to the oxide film, and the concentration of the impurity varies in the film thickness direction from the first main surface on the support substrate side to the second main surface on the group III nitride layer side in the oxide film. The concentration of impurities on the main surface is higher than the concentration of impurities on the second main surface.

本発明にかかるＩＩＩ族窒化物複合基板において、酸化物膜は、第１主面における不純物の濃度を１０質量％以下とし、第２主面における不純物の濃度を０．０１質量％以上とすることができる。また、酸化物膜の不純物の濃度は、酸化物膜において第１主面から第２主面にかけて膜厚方向で単調に変化させることができる。また、支持基板は、窒化物、酸化物および金属からなる群から選ばれる少なくとも１種類を含むことができる。   In the group III nitride composite substrate according to the present invention, the oxide film has an impurity concentration of 10% by mass or less on the first main surface and an impurity concentration of 0.01% by mass or more on the second main surface. Can do. Further, the concentration of impurities in the oxide film can be monotonously changed in the film thickness direction from the first main surface to the second main surface in the oxide film. The support substrate can include at least one selected from the group consisting of nitrides, oxides, and metals.

本発明によれば、支持基板と酸化物膜とＩＩＩ族窒化物層とを含み、支持基板と酸化物膜との接合強度および酸化物膜とＩＩＩ族窒化物層との接合強度が高いＩＩＩ族窒化物複合基板を提供できる。   According to the present invention, the support substrate, the oxide film, and the group III nitride layer are included, and the bond strength between the support substrate and the oxide film and the bond strength between the oxide film and the group III nitride layer are high. A nitride composite substrate can be provided.

本発明にかかるＩＩＩ族窒化物複合基板の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the group III nitride composite substrate concerning this invention. 本発明にかかるＩＩＩ族窒化物複合基板を製造する方法の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the method of manufacturing the group III nitride composite substrate concerning this invention. 酸化物膜と支持基板との接合強度を測定するための積層基板の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the laminated substrate for measuring the joining strength of an oxide film and a support substrate. 酸化物膜とＩＩＩ族窒化物層との接合強度を測定するための積層基板の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of the laminated substrate for measuring the joint strength of an oxide film and a group III nitride layer.

［ＩＩＩ族窒化物複合基板］
図１を参照して、本発明の一実施形態であるＩＩＩ族窒化物複合基板１は、支持基板１０と、支持基板１０上に配置されている酸化物膜２０と、酸化物膜２０上に配置されているＩＩＩ族窒化物層３０ａと、を含む。ここで、支持基板１０は多結晶で形成されている。また、ＩＩＩ族窒化物層３０ａは少なくともｃ軸方向に配向しているＩＩＩ族窒化物結晶で形成されている。また、酸化物膜２０は不純物が添加され、不純物の濃度は、酸化物膜２０において支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向で変化し、第１主面２０ｓにおける不純物の濃度は第２主面２０ｔにおける不純物の濃度よりも高い。 [Group III nitride composite substrate]
Referring to FIG. 1, group III nitride composite substrate 1 according to an embodiment of the present invention includes support substrate 10, oxide film 20 disposed on support substrate 10, and oxide film 20. And a group III nitride layer 30a disposed. Here, the support substrate 10 is formed of polycrystal. The group III nitride layer 30a is formed of a group III nitride crystal oriented at least in the c-axis direction. Further, the oxide film 20 is doped with impurities, and the concentration of the impurities is determined in the film thickness direction from the first main surface 20s on the support substrate 10 side to the second main surface 20t on the group III nitride layer 30a side in the oxide film 20. The concentration of impurities on the first major surface 20s is higher than the concentration of impurities on the second major surface 20t.

本実施形態のＩＩＩ族窒化物複合基板１は、酸化物膜２０における不純物濃度が、支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向で変化し、第１主面２０ｓにおける不純物の濃度が第２主面２０ｔにおける不純物の濃度よりも高いため、支持基板１０と酸化物膜２０との接合強度および酸化物膜２０とＩＩＩ族窒化物層３０ａとの接合強度がいずれも高い。   In the group III nitride composite substrate 1 of this embodiment, the impurity concentration in the oxide film 20 is in the film thickness direction from the first main surface 20s on the support substrate 10 side to the second main surface 20t on the group III nitride layer 30a side. Since the impurity concentration in the first main surface 20s is higher than the impurity concentration in the second main surface 20t, the bonding strength between the support substrate 10 and the oxide film 20 and the oxide film 20 and group III nitride are changed. The bonding strength with the layer 30a is high.

（支持基板）
本実施形態のＩＩＩ族窒化物複合基板１の支持基板１０は、ＩＩＩ族窒化物複合基板１の全体的なコストを低減する観点から、多結晶で形成されている。ここで、多結晶とは、複数の結晶粒からなる結晶をいい、これらの複数の結晶粒が互いに配向していても配向していなくともよい。また、支持基板１０は、多結晶であれば特に制限ないが、低コストである観点から、窒化物、酸化物および金属からなる群から選ばれる少なくとも１種類を含むことが好ましい。 (Support substrate)
From the viewpoint of reducing the overall cost of the group III nitride composite substrate 1, the support substrate 10 of the group III nitride composite substrate 1 of the present embodiment is formed of a polycrystal. Here, the polycrystal means a crystal composed of a plurality of crystal grains, and these crystal grains may or may not be oriented to each other. The support substrate 10 is not particularly limited as long as it is polycrystalline, but it is preferable that the support substrate 10 includes at least one selected from the group consisting of nitrides, oxides, and metals from the viewpoint of low cost.

さらに、ＩＩＩ族窒化物複合基板１のＩＩＩ族窒化物層３０ａ上に半導体層を成長させる際にＩＩＩ族窒化物層３０ａなどにクラックが発生するのを抑制するため、支持基板１０の熱膨張係数はＩＩＩ族窒化物層３０ａの熱膨張係数と同じかまたは近似（両者の熱膨張係数の差が３×１０-6℃-1以下）であることがより好ましい。かかる観点から、支持基板１０は、ＩｎxＡｌyＧａ1-x-yＮ（０≦ｘ、０≦ｙ、ｘ＋ｙ≦１）などのＩＩＩ族窒化物、ムライト（３Ａｌ2Ｏ3・２ＳｉＯ2〜２Ａｌ2Ｏ3・ＳｉＯ2またはＡｌ6Ｏ13Ｓｉ2）などのＡｌ2Ｏ3−ＳｉＯ2系複合酸化物、ＭｇＯ−ＳｉＯ2系複合酸化物、ＭｇＯ−Ａｌ2Ｏ3−ＳｉＯ2系複合酸化物などの酸化物、ならびにＭｏ（モリブデン）、Ｍｏ−Ｃｒ（モリブデン−クロム）合金などの金属の少なくとも１種類を含むことが好ましく、ＩＩＩ族窒化物層を形成するＩＩＩ族窒化物と同じ化学組成のＩＩＩ族窒化物、Ａｌ2Ｏ3−ＳｉＯ2系複合酸化物、Ｍｏなどの少なくとも１種類を含むことがより好ましい。 Further, when the semiconductor layer is grown on the group III nitride layer 30a of the group III nitride composite substrate 1, the thermal expansion coefficient of the support substrate 10 is suppressed in order to suppress the generation of cracks in the group III nitride layer 30a and the like. Is more preferably the same as or close to the thermal expansion coefficient of the group III nitride layer 30a (the difference between the thermal expansion coefficients is 3 × 10 −6 ° C. −1 or less). From this point of view, the supporting substrate 10, In x Al y Ga 1- xy N (0 ≦ x, 0 ≦ y, x + y ≦ 1) III -nitride such as mullite (3Al 2 O 3 · 2SiO 2 ~2Al 2 Al 2 O 3 —SiO 2 complex oxides such as O 3 · SiO 2 or Al 6 O 13 Si 2 ), MgO—SiO 2 complex oxides, MgO—Al 2 O 3 —SiO 2 complex oxides, etc. And at least one metal such as Mo (molybdenum), Mo-Cr (molybdenum-chromium) alloy, and III having the same chemical composition as the group III nitride forming the group III nitride layer. More preferably, it contains at least one kind of group nitride, Al 2 O 3 —SiO 2 composite oxide, Mo, and the like.

（ＩＩＩ族窒化物層）
本実施形態のＩＩＩ族窒化物複合基板１のＩＩＩ族窒化物層３０ａは、ＩＩＩ族窒化物層３０ａ上に品質のよい半導体層を成長させる観点から、少なくともｃ軸方向に配向しているＩＩＩ族窒化物結晶で形成されている。ここで、ＩＩＩ族窒化物結晶は、六方晶系のウルツ鉱型結晶構造を有しており、結晶軸として、同一平面上に互いに１２０°の角度をなして伸びる（すなわち、互いに３回回転対称の位置にある）ａ1軸、ａ2軸およびａ3軸と、その平面に対して垂直に伸びるｃ軸と、を有する。ＩＩＩ族窒化物層３０ａは、上記観点から、ｃ軸方向に加えて、ａ1軸方向、ａ2軸方向およびａ3軸方向のいずれにも配向している結晶、すなわちＩＩＩ族窒化物単結晶であることが好ましい。 (Group III nitride layer)
The group III nitride layer 30a of the group III nitride composite substrate 1 of this embodiment is a group III oriented at least in the c-axis direction from the viewpoint of growing a high-quality semiconductor layer on the group III nitride layer 30a. It is formed of a nitride crystal. Here, the group III nitride crystal has a hexagonal wurtzite crystal structure and extends as a crystal axis at an angle of 120 ° to each other on the same plane (that is, three-fold rotational symmetry with each other). The a 1 axis, the a 2 axis and the a 3 axis (at the position of) and the c axis extending perpendicular to the plane. From the above viewpoint, the group III nitride layer 30a is a crystal oriented in any of the a 1 axis direction, the a 2 axis direction, and the a 3 axis direction in addition to the c axis direction, that is, a group III nitride single crystal It is preferable that

また、ＩＩＩ族窒化物層３０ａの熱膨張係数は、ＩＩＩ族窒化物層３０ａの上に半導体層を形成する際にＩＩＩ族窒化物層３０ａなどにクラックが発生するのを抑制する観点から、支持基板１０の熱膨張係数と同じかまたは近似（両者の熱膨張係数の差が３×１０-6℃-1以下）であるかが好ましい。 Further, the thermal expansion coefficient of the group III nitride layer 30a is supported from the viewpoint of suppressing the generation of cracks in the group III nitride layer 30a and the like when a semiconductor layer is formed on the group III nitride layer 30a. It is preferable that it is the same as or close to the thermal expansion coefficient of the substrate 10 (the difference between the thermal expansion coefficients of both is 3 × 10 −6 ° C. −1 or less).

（酸化物膜）
本実施形態のＩＩＩ族窒化物複合基板１の酸化物膜２０は、不純物が添加されている。ここで、不純物の濃度は、酸化物膜２０において支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向で変化し、第１主面２０ｓにおける不純物の濃度は第２主面２０ｔにおける不純物の濃度よりも高い。 (Oxide film)
Impurities are added to the oxide film 20 of the group III nitride composite substrate 1 of the present embodiment. Here, the impurity concentration in the oxide film 20 changes in the film thickness direction from the first main surface 20s on the support substrate 10 side to the second main surface 20t on the group III nitride layer 30a side, and the first main surface 20s. The concentration of impurities at is higher than the concentration of impurities at the second major surface 20t.

後述するように、ＩＩＩ族窒化物多結晶で形成されている支持基板１０と酸化物膜２０との接合強度は、酸化物膜２０に不純物が添加されていないときに比べて不純物が添加されその不純物の濃度が高くなる程、高くなる。また、酸化物膜２０と少なくともｃ軸方向に配向しているＩＩＩ族窒化物結晶（好ましくはＩＩＩ族窒化物単結晶）で形成されているＩＩＩ族窒化物層３０ａとの接合強度は、酸化物膜２０に不純物が添加されていないときに比べて不純物が添加されその不純物の濃度が高くなる程、低くなる。   As will be described later, the bonding strength between the support substrate 10 formed of group III nitride polycrystal and the oxide film 20 is higher than that when no impurity is added to the oxide film 20. The higher the impurity concentration, the higher the impurity concentration. Further, the bonding strength between the oxide film 20 and the group III nitride layer 30a formed of a group III nitride crystal (preferably a group III nitride single crystal) oriented at least in the c-axis direction is an oxide. Compared with the case where no impurity is added to the film 20, the impurity is added and the concentration of the impurity is increased, so that it is lowered.

したがって、酸化物膜２０において、支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向で不純物の濃度を変化させ、第１主面２０ｓにおける不純物の濃度を第２主面２０ｔにおける不純物の濃度よりも高くすることにより、支持基板１０と酸化物膜２０との接合強度および酸化物膜２０とＩＩＩ族窒化物層３０ａとの接合強度がいずれも高いＩＩＩ族窒化物複合基板１が得られる。また、酸化物膜２０は、不純物が添加されることにより、導電性が高くなる。ここで、酸化物膜２０における不純物の存在および濃度は、ＳＩＭＳ（２次イオン質量分析）法により測定される。   Therefore, in the oxide film 20, the concentration of impurities is changed in the film thickness direction from the first main surface 20s on the support substrate 10 side to the second main surface 20t on the group III nitride layer 30a side, and the first main surface 20s By making the impurity concentration higher than the impurity concentration on the second main surface 20t, the bonding strength between the support substrate 10 and the oxide film 20 and the bonding strength between the oxide film 20 and the group III nitride layer 30a are increased. Higher Group III nitride composite substrate 1 can be obtained. Further, the conductivity of the oxide film 20 is increased by adding impurities. Here, the presence and concentration of impurities in the oxide film 20 are measured by a SIMS (secondary ion mass spectrometry) method.

さらに、支持基板１０と酸化物膜２０との接合強度および酸化物膜２０とＩＩＩ族窒化物層３０ａとの接合強度がいずれも十分に高くする観点から、酸化物膜２０は、第１主面２０ｓにおける不純物の濃度が１０質量％以下であり、第２主面２０ｔにおける不純物の濃度が０．０１質量％以上であることが好ましい。また、酸化物膜２０における不純物の濃度を、膜厚方向で最も低いところ（たとえば第２主面２０ｔ）においても、０．０１質量％以上とすることにより、ＩＩＩ族窒化物複合基板１の膜厚方向における導電性が確保される。   Furthermore, from the viewpoint of sufficiently increasing the bonding strength between the support substrate 10 and the oxide film 20 and the bonding strength between the oxide film 20 and the group III nitride layer 30a, the oxide film 20 has the first main surface. The impurity concentration in 20 s is preferably 10% by mass or less, and the impurity concentration in the second main surface 20t is preferably 0.01% by mass or more. Further, by setting the concentration of impurities in oxide film 20 to 0.01% by mass or more even at the lowest position in the film thickness direction (for example, second main surface 20t), film of group III nitride composite substrate 1 is obtained. Conductivity in the thickness direction is ensured.

さらに、光透過性が高い観点から、酸化物膜２０の不純物の濃度は、酸化物膜２０において第１主面２０ｓから第２主面２０ｔにかけて膜厚方向で単調に変化することが好ましい。ここで、単調に変化するとは、酸化物膜２０の膜厚方向の任意の位置ｘ1、ｘ2（ｘ1＜ｘ2）における不純物の濃度ｆ（ｘ1）、ｆ（ｘ2）において、ｆ（ｘ1）＜ｆ（ｘ2）（単調増加）またはｆ（ｘ1）＞ｆ（ｘ2）（単調減少）であることをいう。 Further, from the viewpoint of high light transmittance, it is preferable that the impurity concentration of the oxide film 20 changes monotonously in the film thickness direction from the first main surface 20s to the second main surface 20t in the oxide film 20. Here, the monotonous change means that the impurity concentrations f (x 1 ) and f (x 2 ) at arbitrary positions x 1 and x 2 (x 1 <x 2 ) in the film thickness direction of the oxide film 20 are: It means that f (x 1 ) <f (x 2 ) (monotonic increase) or f (x 1 )> f (x 2 ) (monotonic decrease).

ここで、酸化物膜２０は、支持基板１０とＩＩＩ族窒化物層３０ａとの間の接合強度を高めるものであれば特に制限はないが、安価に成膜できる観点からＳｉＯ2膜などが好ましく挙げられ、その酸化物膜の屈折率がＧａＮなどのＩＩＩ族窒化物結晶の屈折率に近く、酸化物膜とＩＩＩ族窒化物結晶との界面で高い光透過性を有する観点からＴｉＯ2膜、ＳｒＴｉＯ3膜などが好ましく挙げられ、その酸化物膜を損なうことなく安定した不純物の添加ができる観点から、ＴｉＯ2膜には不純物としてＮｂ、Ｌａ、Ｓｂ、Ｍｏ、Ｆｅ、Ａｌ、Ｓｎ、Ｐｔ、Ｉ、Ｂ、Ｎなどが添加されることが好ましく、ＳｒＴｉＯ3膜には不純物としてＬａ、Ｎｂ、Ｓｂ、Ｍｏ、Ｆｅ、Ａｌ、Ｓｎ、Ｐｔ、Ｉ、Ｂ、Ｎなどが添加されることが好ましい。 Here, the oxide film 20 is not particularly limited as long as it increases the bonding strength between the support substrate 10 and the group III nitride layer 30a, but a SiO 2 film or the like is preferable from the viewpoint of being able to form the film at a low cost. TiO 2 film from the viewpoint that the refractive index of the oxide film is close to the refractive index of a group III nitride crystal such as GaN, and has high optical transparency at the interface between the oxide film and the group III nitride crystal, such as SrTiO 3 film is preferably exemplified, Nb from the viewpoint of the addition of a stable impurity without sacrificing the oxide film, as an impurity in the TiO 2 film, La, Sb, Mo, Fe , Al, Sn, Pt, I, B, N, etc. are preferably added, and La, Nb, Sb, Mo, Fe, Al, Sn, Pt, I, B, N, etc. are preferably added as impurities to the SrTiO 3 film. .

［ＩＩＩ族窒化物複合基板の製造方法］
図２を参照して、本実施形態のＩＩＩ族窒化物複合基板１を製造する方法は、特に制限はないが、効率よく製造する観点から、たとえば、以下の方法が、好適に挙げられる。 [Method for producing group III nitride composite substrate]
Referring to FIG. 2, the method for manufacturing group III nitride composite substrate 1 of the present embodiment is not particularly limited, but from the viewpoint of efficiently manufacturing, for example, the following method is preferably exemplified.

すなわち、ＩＩＩ族窒化物複合基板１の製造方法は、支持基板１０の主面１０ｍ上に酸化物膜２０ａを形成する工程（図２（Ａ））と、ＩＩＩ族窒化物基板３０の主面３０ｎ上に酸化物膜２０ｂを形成し、ＩＩＩ族窒化物基板３０の主面３０ｎから所定の深さの位置にイオン注入領域３０ｉを形成する工程（図２（Ｂ））と、支持基板１０に形成された酸化物膜２０ａとＩＩＩ族窒化物基板３０に形成された酸化物膜２０ｂとを貼り合わせる工程（図２（Ｃ））と、ＩＩＩ族窒化物基板３０をイオン注入領域３０ｉにおいてＩＩＩ族窒化物層３０ａと残りのＩＩＩ族窒化物基板３０ｂとに分離することにより、支持基板１０上に酸化物膜２０を介在させてＩＩＩ族窒化物層３０ａが接合されたＩＩＩ族窒化物複合基板を形成する工程（図２（Ｄ））と、を含む。   That is, the manufacturing method of the group III nitride composite substrate 1 includes the step of forming the oxide film 20a on the main surface 10m of the support substrate 10 (FIG. 2A) and the main surface 30n of the group III nitride substrate 30. An oxide film 20b is formed thereon, and a step (FIG. 2B) of forming an ion implantation region 30i at a predetermined depth from the main surface 30n of the group III nitride substrate 30 is formed on the support substrate 10. A step of bonding the formed oxide film 20a and the oxide film 20b formed on the group III nitride substrate 30 (FIG. 2C), and the group III nitride substrate 30 in the ion implantation region 30i. By separating the material layer 30a and the remaining group III nitride substrate 30b, a group III nitride composite substrate in which the group III nitride layer 30a is bonded to the support substrate 10 with the oxide film 20 interposed therebetween is formed. Step (Fig. 2 ( )) And, including.

（支持基板に酸化物膜を形成する工程）
図２（Ａ）を参照して、支持基板１０の主面１０ｍ上に酸化物膜２０ａを形成する工程において、酸化物膜２０ａを形成する方法は、特に制限はなく、スパッタ法、パルスレーザ堆積法、ＭＢＥ（分子線成長）法、電子線蒸着法、化学気相成長法などが好適である。また、酸化物膜の形成中に、不純物の添加量を変化させることにより、酸化物膜の膜厚方向において不純物の濃度を変化させることができる。支持基板１０としては、半導体層形成の際にコストを低減しクラックの発生を抑制する観点から、ＩＩＩ族窒化物多結晶支持基板が用いられ、特に、ＩＩＩ族窒化物焼結体が好適に用いられる。また、酸化物膜２０ａとしては、特に制限はなく、ＳｉＯ2膜、ＴｉＯ2膜、ＳｒＴｉＯ3膜などが好適に形成される。 (Step of forming an oxide film on the support substrate)
Referring to FIG. 2A, in the step of forming the oxide film 20a on the main surface 10m of the support substrate 10, the method for forming the oxide film 20a is not particularly limited, and a sputtering method, pulse laser deposition is performed. The method, MBE (molecular beam growth) method, electron beam evaporation method, chemical vapor deposition method and the like are suitable. Further, the impurity concentration can be changed in the thickness direction of the oxide film by changing the addition amount of the impurity during the formation of the oxide film. As the support substrate 10, a group III nitride polycrystalline support substrate is used from the viewpoint of reducing the cost and suppressing the occurrence of cracks when forming the semiconductor layer, and in particular, a group III nitride sintered body is preferably used. It is done. The oxide film 20a is not particularly limited, and a SiO 2 film, a TiO 2 film, a SrTiO 3 film, or the like is preferably formed.

（ＩＩＩ族窒化物基板に酸化物膜を形成しイオン注入領域を形成する工程）
図２（Ｂ）を参照して、ＩＩＩ族窒化物基板３０の主面３０ｎ上に酸化物膜２０ｂを形成し、ＩＩＩ族窒化物基板３０の主面３０ｎから所定の深さの位置にイオン注入領域３０ｉを形成する工程において、酸化物膜２０ｂを形成する方法は、特に制限はなく、上記の酸化物膜２０ａを形成する方法と同様である。また、ＩＩＩ族窒化物基板３０の主面３０ｎから所定の深さの位置にイオン注入領域３０ｉを形成する方法は、ＩＩＩ族窒化物基板３０の主面３０ｎ上に形成された酸化物膜２０ｂ側からイオンＩを注入することにより行なう。注入するイオンＩは、イオン注入されるＩＩＩ族窒化物層３０ａの結晶性の低下を抑制する観点から、質量の小さいイオンが好ましく、たとえば水素イオン、ヘリウムイオンなどが好ましい。また、イオンＩが注入される所定の深さは、５００ｎｍ以上１０００μｍ以下が好ましい。 (Process for forming an ion implantation region by forming an oxide film on a group III nitride substrate)
Referring to FIG. 2B, oxide film 20b is formed on main surface 30n of group III nitride substrate 30, and ion implantation is performed at a predetermined depth from main surface 30n of group III nitride substrate 30. In the step of forming the region 30i, the method for forming the oxide film 20b is not particularly limited, and is the same as the method for forming the oxide film 20a. In addition, the method of forming the ion implantation region 30i at a predetermined depth from the main surface 30n of the group III nitride substrate 30 is based on the oxide film 20b side formed on the main surface 30n of the group III nitride substrate 30. Ion I is implanted from The ions I to be implanted are preferably ions with a small mass, for example, hydrogen ions, helium ions, etc., from the viewpoint of suppressing a decrease in crystallinity of the group III nitride layer 30a to be ion implanted. Further, the predetermined depth at which the ions I are implanted is preferably 500 nm or more and 1000 μm or less.

ここで、ＩＩＩ族窒化物基板３０は、後工程における分離によりＩＩＩ族窒化物層３０ａを形成させるものであり、ＩＩＩ族窒化物層３０ａと同様に、少なくともｃ軸方向に配向しているＩＩＩ族窒化物結晶（好ましくはＩＩＩ族窒化物単結晶）で形成されている。かかるＩＩＩ族窒化物基板を準備する方法は、特に制限はないが、結晶性のよいＩＩＩ族窒化物基板を得る観点から、ＨＶＰＥ（ハイドライド気相成長）法、ＭＯＶＰＥ（有機金属気相成長）法、ＭＢＥ（分子線成長）法、昇華法などの気相法、フラックス法、高窒素圧溶液法などの液相法などが好適である。   Here, the group III nitride substrate 30 is to form the group III nitride layer 30a by separation in a later step, and like the group III nitride layer 30a, the group III nitride is oriented at least in the c-axis direction. It is formed of a nitride crystal (preferably a group III nitride single crystal). The method for preparing such a group III nitride substrate is not particularly limited, but from the viewpoint of obtaining a group III nitride substrate having good crystallinity, the HVPE (hydride vapor phase epitaxy) method, the MOVPE (organometallic vapor phase epitaxy) method. A vapor phase method such as MBE (molecular beam growth) method and sublimation method, a liquid phase method such as a flux method and a high nitrogen pressure solution method are suitable.

（支持基板とＩＩＩ族窒化物基板との貼り合わせ工程）
図２（Ｃ）を参照して、支持基板１０に形成された酸化物膜２０ａとＩＩＩ族窒化物基板３０に形成された酸化物膜２０ｂとを貼り合わせる工程において、その貼り合わせ方法は、特に制限はなく、貼り合わせ面を洗浄しそのまま貼り合わせた後６００℃〜１２００℃程度に昇温して接合する直接接合法、貼り合わせ面を洗浄しプラズマやイオンなどで活性させた後に室温（たとえば２５℃）〜４００℃程度の低温で接合する表面活性化法などが好適である。かかる貼り合わせにより、酸化物膜２０ａと酸化物膜２０ｂとが接合により一体化して酸化物膜２０が形成され、支持基板１０とＩＩＩ族窒化物基板３０とが酸化物膜２０を介在させて接合される。 (Bonding process of support substrate and group III nitride substrate)
Referring to FIG. 2C, in the step of bonding the oxide film 20a formed on the support substrate 10 and the oxide film 20b formed on the group III nitride substrate 30, the bonding method is particularly There is no limitation, a direct bonding method in which the bonding surface is washed and bonded together, and then heated to about 600 ° C. to 1200 ° C. for bonding, and the bonding surface is cleaned and activated with plasma, ions, or the like at room temperature (for example, A surface activation method for bonding at a low temperature of about 25 ° C. to 400 ° C. is preferable. By the bonding, the oxide film 20a and the oxide film 20b are integrated by bonding to form the oxide film 20, and the support substrate 10 and the group III nitride substrate 30 are bonded with the oxide film 20 interposed therebetween. Is done.

（ＩＩＩ族窒化物複合基板の形成工程）
図２（Ｄ）を参照して、ＩＩＩ族窒化物基板３０をイオン注入領域３０ｉにおいてＩＩＩ族窒化物層３０ａと残りのＩＩＩ族窒化物基板３０ｂとに分離することにより、支持基板１０上に酸化物膜２０を介在させてＩＩＩ族窒化物層３０ａが接合されたＩＩＩ族窒化物複合基板１を形成する工程において、ＩＩＩ族窒化物基板３０をイオン注入領域３０ｉにおいて分離する方法は、ＩＩＩ族窒化物基板３０のイオン注入領域３０ｉに何らかのエネルギーを与える方法であれば特に制限はなく、イオン注入領域３０ｉに、応力を加える方法、熱を加える方法、光を照射する方法、および超音波を印加する方法の少なくともいずれかの方法が可能である。 (Group III nitride composite substrate formation process)
Referring to FIG. 2D, the group III nitride substrate 30 is separated into a group III nitride layer 30a and a remaining group III nitride substrate 30b in the ion implantation region 30i, thereby oxidizing the support substrate 10 on the substrate. The method of separating the group III nitride substrate 30 in the ion implantation region 30i in the step of forming the group III nitride composite substrate 1 to which the group III nitride layer 30a is bonded with the material film 20 interposed therebetween is a group III nitridation method. There is no particular limitation as long as it is a method for applying some energy to the ion implantation region 30i of the physical substrate 30, and a method of applying stress, a method of applying heat, a method of irradiating light, and an ultrasonic wave are applied to the ion implantation region 30i. At least one of the methods is possible.

かかるイオン注入領域３０ｉは、注入されたイオンにより脆化しているため、上記エネルギーを受けることにより、ＩＩＩ族窒化物基板３０は、支持基板１０上の酸化物膜２０上に貼りあわされたＩＩＩ族窒化物層３０ａと、残りのＩＩＩ族窒化物基板３０ｂと、に容易に分離される。   Since the ion-implanted region 30i is embrittled by the implanted ions, the group III nitride substrate 30 is subjected to the above-described energy, so that the group III nitride substrate 30 bonded to the oxide film 20 on the support substrate 10 is used. The nitride layer 30a and the remaining group III nitride substrate 30b are easily separated.

上記のようにして、支持基板１０上の酸化物膜２０上にＩＩＩ族窒化物層３０ａを形成することにより、支持基板１０と、支持基板１０上に配置されている酸化物膜２０と、酸化物膜２０上に配置されているＩＩＩ族窒化物層３０ａと、を含むＩＩＩ族窒化物複合基板１が得られる。   By forming the group III nitride layer 30a on the oxide film 20 on the support substrate 10 as described above, the support substrate 10, the oxide film 20 disposed on the support substrate 10, and the oxidation The group III nitride composite substrate 1 including the group III nitride layer 30a disposed on the material film 20 is obtained.

上記のＩＩＩ族窒化物複合基板１の製造方法においては、イオン注入法を用いてＩＩＩ族窒化物層３０ａを形成する場合を説明したが、支持基板上の酸化物膜に、イオンを注入していないＩＩＩ族窒化物基板を貼り合わせた後、ＩＩＩ族窒化物結晶体をその貼り合わせた主表面から所定の深さの面で分離することにより、ＩＩＩ族窒化物層を形成することもできる。この場合、ＩＩＩ族窒化物基板を分離する方法として、特に制限はなく、ワイヤーソー、内周刃、外周刃などを用いた切断などの方法を用いることができる。   In the manufacturing method of the group III nitride composite substrate 1 described above, the case where the group III nitride layer 30a is formed using the ion implantation method has been described. However, ions are implanted into the oxide film on the support substrate. It is also possible to form a group III nitride layer by separating a group III nitride crystal from a main surface to which the group III nitride crystal body has been bonded and having a predetermined depth after the group III nitride substrate is bonded. In this case, the method for separating the group III nitride substrate is not particularly limited, and a method such as cutting using a wire saw, an inner peripheral blade, an outer peripheral blade or the like can be used.

（参考例Ａ）
図１を参照して、多結晶（焼結体）で形成される直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＧａＮ支持基板（支持基板１０）、直径２インチ（５０．８ｍｍ）で厚さが６００ｎｍのＴｉＯ2膜（酸化物膜２０）および単結晶で形成される直径２インチ（５０．８ｍｍ）で厚さが３００ｎｍのＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、ＴｉＯ2膜（酸化物膜２０）中のＮｂ（不純物）の濃度と、ＴｉＯ2膜（酸化物膜２０）とＧａＮ支持基板（支持基板１０）との接合強度との関係、ならびに、ＴｉＯ2膜（酸化物膜２０）中のＮｂ（不純物）の濃度と、ＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度との関係を、以下のようにして調べた。 (Reference Example A)
Referring to FIG. 1, a GaN support substrate (support substrate 10) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm formed of polycrystal (sintered body), and a thickness of 2 inches (50.8 mm). A TiO 2 film (oxide film 20) having a thickness of 600 nm and a GaN layer (group III nitride layer 30a) having a diameter of 2 inches (50.8 mm) and a thickness of 300 nm formed of a single crystal are joined in this order. for GaN composite substrate (III-nitride composite substrate 1), a TiO 2 film (oxide film 20) and the concentration of Nb (impurities) in, GaN supporting substrate and TiO 2 film (oxide film 20) (supporting substrate 10 ) relationship between the bonding strength between, and the concentration of Nb (impurities) in the TiO 2 film (oxide film 20), a TiO 2 film (oxide film 20) and the GaN layer (III-nitride layer 30a) The relationship with the bonding strength is as follows: It was examined Te.

１．酸化物膜中の不純物の濃度と、酸化物膜と支持基板との接合強度と、の関係
（１）サンプルの作製
図３を参照して、以下のようにして、酸化物膜２０と支持基板１０との接合強度を測定するためのサンプルを作製した。 1. Relationship between impurity concentration in oxide film and bonding strength between oxide film and supporting substrate (1) Production of sample Referring to FIG. 3, oxide film 20 and supporting substrate are as follows. A sample for measuring the bonding strength with No. 10 was prepared.

まず、ＨＰ（ホットプレス）法により形成された多結晶（焼結体）である直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＧａＮ支持基板（支持基板１０）の主面上に、スパッタ法により厚さ６００ｎｍのＴｉＯ2膜（酸化物膜２０）を形成させることにより、ＧａＮ支持基板（支持基板１０）の主面上にＴｉＯ2膜（酸化物膜２０）が形成された積層基板１Ｓを作製した。ここで、成長させるＴｉＯ2膜（酸化物膜）のＮｂ（不純物）の濃度が、０質量％、０．０１質量％、０．１質量％、１質量％および１０質量％の５種類の積層基板１Ｓを作製した。 First, a sputtering method is performed on the main surface of a GaN support substrate (support substrate 10) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm, which is a polycrystal (sintered body) formed by an HP (hot press) method. By forming a TiO 2 film (oxide film 20) having a thickness of 600 nm by the above, a laminated substrate 1S in which the TiO 2 film (oxide film 20) is formed on the main surface of the GaN support substrate (support substrate 10) is formed. Produced. Here, five kinds of stacks in which the concentration of Nb (impurity) of the TiO 2 film (oxide film) to be grown is 0% by mass, 0.01% by mass, 0.1% by mass, 1% by mass, and 10% by mass. A substrate 1S was produced.

次いで、得られた積層基板１Ｓを１２ｍｍ×１２ｍｍの大きさにチップ化することにより、１種類の積層基板１Ｓについて９個のサンプルを得た。   Next, nine samples were obtained for one type of laminated substrate 1S by chipping the obtained laminated substrate 1S into a size of 12 mm × 12 mm.

（２）サンプルの接合強度の測定
上記サンプルのＧａＮ支持基板（支持基板）およびＴｉＯ2膜（酸化物膜）をそれぞれ引張試験機の治具にエポキシ接着剤を用いて固定し、ＧａＮ支持基板（支持基板）とＴｉＯ2膜（酸化物膜）とを引張ることにより、ＧａＮ支持基板（支持基板）とＴｉＯ2膜（酸化物膜）との間の接合強度（９個のサンプルの平均値、以下同じ）を測定した。各種の積層基板１Ｓのサンプルの接合強度は、ＴｉＯ2膜（酸化物膜）のＮｂ（不純物）の濃度が０質量％のときの積層基板１Ｓのサンプルの接合強度を１．００としたときの相対接合強度として算出した。 (2) Measurement of bonding strength of sample The GaN support substrate (support substrate) and TiO 2 film (oxide film) of the above sample were each fixed to a jig of a tensile tester using an epoxy adhesive, and a GaN support substrate ( by supporting substrate) and pulling the TiO 2 film (oxide film), the average value of the bonding strength (nine samples between the GaN supporting substrate (supporting substrate) and TiO 2 film (oxide film), the following The same). The bonding strength of the samples of various laminated substrates 1S is obtained when the bonding strength of the samples of the laminated substrates 1S when the Nb (impurity) concentration of the TiO 2 film (oxide film) is 0% by mass is 1.00. The relative bonding strength was calculated.

上記の引張試験において、上記のいずれの積層基板１Ｓのいずれのサンプルも、ＧａＮ支持基板（支持基板）とＴｉＯ2膜（酸化物膜）との界面または界面の近傍で破断した。 In the tensile test, any sample of any one of the laminated substrates 1S was broken at or near the interface between the GaN support substrate (support substrate) and the TiO 2 film (oxide film).

また、各種積層基板１Ｓの接合強度は、Ｎｂ（不純物）の濃度が０質量％のとき１．００、Ｎｂ（不純物）の濃度が０．０１質量％のとき１．０１、Ｎｂ（不純物）の濃度が０．１質量％のとき１．０２、Ｎｂ（不純物）の濃度が１質量％のとき１．４０、Ｎｂ（不純物）の濃度が１０質量％のとき１．１０であった。すなわち、Ｎｂ（不純物）の濃度が０質量％のときに比べて、Ｎｂ（不純物）の濃度が０．０１質量％〜１０質量％のときは、ＴｉＯ2膜（酸化物膜）とＧａＮ支持基板（支持基板）との間の接合強度が高くなった。結果を表１にまとめた。 The bonding strength of the various laminated substrates 1S is 1.00 when the concentration of Nb (impurity) is 0% by mass, 1.01 when the concentration of Nb (impurity) is 0.01% by mass, and Nb (impurity). The concentration was 1.02 when the concentration was 0.1% by mass, 1.40 when the concentration of Nb (impurity) was 1% by mass, and 1.10 when the concentration of Nb (impurity) was 10% by mass. That is, when the concentration of Nb (impurity) is 0.01% by mass to 10% by mass compared to when the concentration of Nb (impurity) is 0% by mass, the TiO 2 film (oxide film) and the GaN support substrate The bonding strength with the (support substrate) was increased. The results are summarized in Table 1.

２．酸化物膜中の不純物の濃度と、酸化物膜とＩＩＩ族窒化物層との接合強度と、の関係
（１）サンプルの作製
図４を参照して、以下のようにして、酸化物膜とＩＩＩ族窒化物層との接合強度を測定するためのサンプルを作製した。 2. Relationship between impurity concentration in oxide film and bonding strength between oxide film and group III nitride layer (1) Preparation of sample Referring to FIG. A sample for measuring the bonding strength with the group III nitride layer was prepared.

まず、直径２インチ（５０．８ｍｍ）で厚さ５００μｍのサファイア支持基板１００の主面上に、スパッタ法により厚さ３００ｎｍのＴｉＯ2膜（酸化物膜２０ａ）を形成した。ここで、成長させるＴｉＯ2膜（酸化物膜２０ａ）は、そのＮｂ（不純物）の濃度が、０質量％、０．０１質量％、０．１質量％、１質量％および１０質量％の５種類とした。 First, a 300 nm thick TiO 2 film (oxide film 20a) was formed by sputtering on the main surface of a sapphire support substrate 100 having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm. Here, the TiO 2 film to be grown (oxide film 20a) has a Nb (impurity) concentration of 5% of 0 mass%, 0.01 mass%, 0.1 mass%, 1 mass%, and 10 mass%. Kind.

次に、ＨＶＰＥ法により形成された単結晶である直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＧａＮ基板（ＩＩＩ族窒化物基板３０）のＮ原子表面である主面上に、スパッタ法により厚さ３００ｎｍのＴｉＯ2膜（酸化物膜２０ｂ）を形成させた。ここで、成長させるＴｉＯ2膜（酸化物膜２０ｂ）は、そのＮｂ（不純物）の濃度が、０質量％、０．０１質量％、０．１質量％、１質量％および１０質量％の５種類とした。 Next, the main surface, which is the N atom surface of a GaN substrate (group III nitride substrate 30) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm, which is a single crystal formed by HVPE, is sputtered. A TiO 2 film (oxide film 20b) having a thickness of 300 nm was formed. Here, the TiO 2 film to be grown (oxide film 20b) has a Nb (impurity) concentration of 5% of 0 mass%, 0.01 mass%, 0.1 mass%, 1 mass%, and 10 mass%. Kind.

次いで、上記５種類のＴｉＯ2膜（酸化物膜２０ｂ）が形成されたＧａＮ基板（ＩＩＩ族窒化物基板３０）のＴｉＯ2膜（酸化物膜２０ｂ）側から水素イオンを注入して、ＧａＮ基板（ＩＩＩ族窒化物基板）のＮ原子表面である主面から３００ｎｍの深さの位置にイオン注入領域を形成した。 Next, hydrogen ions are implanted from the TiO 2 film (oxide film 20b) side of the GaN substrate (Group III nitride substrate 30) on which the five types of TiO 2 films (oxide film 20b) are formed, and the GaN substrate is obtained. An ion-implanted region was formed at a depth of 300 nm from the main surface which is the N atom surface of (Group III nitride substrate).

次に、サファイア支持基板１００に形成されたＴｉＯ2膜（酸化物膜２０ａ）と、イオン注入領域が形成されたＧａＮ基板（ＩＩＩ族窒化物基板）に形成されたＴｉＯ2膜（酸化物膜２０ｂ）とを、貼り合わせた。ここで、貼り合わせるＴｉＯ2膜（酸化物膜２０ａと酸化物膜２０ｂ）は、それらに含まれるＮｂ濃度が互いに同じであるもの同士とした。 Next, a TiO 2 film formed on the sapphire support substrate 100 (oxide film 20a), TiO 2 film (oxide film 20b formed on the GaN substrate ion implantation region is formed (III-nitride substrate) ). Here, the TiO 2 films (the oxide film 20a and the oxide film 20b) to be bonded together have the same Nb concentration in them.

次に、上記で貼り合わせた基板を、３００℃で２時間熱処理することにより、貼り合わせた基板の接合強度を高めるとともに、ＧａＮ基板（ＩＩＩ族窒化物基板）をイオン注入領域で分離することにより、サファイア支持基板１００上にＴｉＯ2膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合され、ＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）濃度が、それぞれ０質量％、０．０１質量％、０．１質量％、１質量％および１０質量％の５種類である積層基板１Ｔを作製した。 Next, the bonded substrates are heat-treated at 300 ° C. for 2 hours to increase the bonding strength of the bonded substrates and to separate the GaN substrate (Group III nitride substrate) in the ion implantation region. The TiO 2 film (oxide film 20) and the GaN layer (group III nitride layer 30a) are joined in this order on the sapphire support substrate 100, and the Nb (impurity) concentration of the TiO 2 film (oxide film 20) is 5 types of laminated substrates 1T, each of 0% by mass, 0.01% by mass, 0.1% by mass, 1% by mass and 10% by mass, were produced.

（２）サンプルの接合強度の測定
上記サンプルのサファイア支持基板１００およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）をそれぞれ引張試験機の治具にエポキシ接着剤を用いて固定し、サファイア支持基板１００とＧａＮ層（ＩＩＩ族窒化物層３０ａ）とを引張ることにより、ＧａＮ層（ＩＩＩ族窒化物層３０ａ）とＴｉＯ2膜（酸化物膜２０）との間の接合強度を測定した。各種の積層基板１Ｔのサンプルの接合強度は、ＴｉＯ2膜（酸化物膜）のＮｂ（不純物）の濃度が０質量％のときの積層基板１Ｔのサンプルの接合強度を１．００としたときの相対接合強度として算出した。 (2) Measurement of bonding strength of sample The sapphire support substrate 100 and the GaN layer (Group III nitride layer 30a) of the above sample are each fixed to a jig of a tensile tester using an epoxy adhesive, and the sapphire support substrate 100 and The bonding strength between the GaN layer (Group III nitride layer 30a) and the TiO 2 film (oxide film 20) was measured by pulling the GaN layer (Group III nitride layer 30a). The bonding strength of the samples of the various laminated substrates 1T is obtained when the bonding strength of the samples of the laminated substrate 1T when the Nb (impurity) concentration of the TiO 2 film (oxide film) is 0% by mass is 1.00. The relative bonding strength was calculated.

上記の引張試験において、上記のいずれの積層基板１Ｔのいずれのサンプルも、ＧａＮ層（ＩＩＩ族窒化物層３０ａ）とＴｉＯ2膜（酸化物膜２０）との界面または界面の近傍で破断した。 In the tensile test, any sample of any one of the multilayer substrates 1T was broken at or near the interface between the GaN layer (Group III nitride layer 30a) and the TiO 2 film (oxide film 20).

また、各種積層基板１Ｔの接合強度は、Ｎｂ（不純物）の濃度が０質量％のとき１．００、Ｎｂ（不純物）の濃度が０．０１質量％のとき０．７８、Ｎｂ（不純物）の濃度が０．１質量％のとき０．７２、Ｎｂ（不純物）の濃度が１質量％のとき０．５６、Ｎｂ（不純物）の濃度が１０質量％のとき０．５５であった。すなわち、Ｎｂ（不純物）の濃度が０質量％のときに比べて、Ｎｂ（不純物）の濃度が０．０１質量％から１０質量％と高くなる程、ＴｉＯ2膜（酸化物膜）とＧａＮ層（ＩＩＩ族窒化物層）との間の接合強度が低くなった。結果を表１にまとめた。 Further, the bonding strength of the various laminated substrates 1T is 1.00 when the concentration of Nb (impurity) is 0 mass%, 0.78 when the concentration of Nb (impurity) is 0.01 mass%, and Nb (impurity). The concentration was 0.72 when the concentration was 0.1% by mass, 0.56 when the concentration of Nb (impurity) was 1% by mass, and 0.55 when the concentration of Nb (impurity) was 10% by mass. That is, as the Nb (impurity) concentration increases from 0.01% by mass to 10% by mass compared to when the Nb (impurity) concentration is 0% by mass, the TiO 2 film (oxide film) and the GaN layer The bonding strength with the (Group III nitride layer) was low. The results are summarized in Table 1.

Figure 2013084900
Figure 2013084900

図１および表１を参照して、ＧａＮ支持基板（支持基板１０）、ＴｉＯ2膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）において、ＴｉＯ2膜（酸化物膜２０）とＧａＮ支持基板（支持基板１０）との接合強度を高めるにはＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）濃度を高くすることが有効であり（特に、不純物濃度を１質量％程度とするのが好ましく）、ＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度を高めるにはＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）濃度を低くすることが有効であることがわかった。 Referring to FIG. 1 and Table 1, a GaN composite substrate (III) in which a GaN support substrate (support substrate 10), a TiO 2 film (oxide film 20), and a GaN layer (group III nitride layer 30a) are joined in this order. In the group nitride composite substrate 1), the Nb (impurity) concentration of the TiO 2 film (oxide film 20) is increased in order to increase the bonding strength between the TiO 2 film (oxide film 20) and the GaN support substrate (support substrate 10). Is effective (especially, the impurity concentration is preferably about 1% by mass), and the bonding strength between the TiO 2 film (oxide film 20) and the GaN layer (group III nitride layer 30a) is increased. It has been found that it is effective to lower the Nb (impurity) concentration of the TiO 2 film (oxide film 20) in order to increase it.

（実施例Ａ）
１．支持基板の主面上への酸化物膜の形成
図２（Ａ）を参照して、ＨＰ法により形成された多結晶（焼結体）である直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＧａＮ支持基板（支持基板１０）の主面上に、スパッタ法により厚さ３００ｎｍのＴｉＯ2膜（酸化物膜２０ａ）を形成させた。ここで、成長させるＴｉＯ2膜（酸化物膜２０ａ）は、そのＮｂ（不純物）の濃度を、ＧａＮ支持基板（支持基板１０）側から膜厚方向に、１質量％から０．５質量％（例Ａ１）、１質量％から０．５質量％（例Ａ２）、１０質量％から５質量％（例Ａ３）、１質量％から１０質量％（例Ａ４）と単調に変化させて、上記例Ａ１から例Ａ４の４種類とした。 (Example A)
1. Formation of Oxide Film on Main Surface of Support Substrate Referring to FIG. 2 (A), a polycrystal (sintered body) formed by the HP method has a diameter of 2 inches (50.8 mm) and a thickness of 500 μm. A TiO 2 film (oxide film 20a) having a thickness of 300 nm was formed on the main surface of the GaN support substrate (support substrate 10) by sputtering. Here, the TiO 2 film (oxide film 20a) to be grown has a Nb (impurity) concentration of 1% by mass to 0.5% by mass in the film thickness direction from the GaN support substrate (support substrate 10) side. Example A1) 1% to 0.5% by weight (Example A2) 10% to 5% by weight (Example A3) 1% to 10% by weight (Example A4) There were four types from A1 to Example A4.

２．ＩＩＩ族窒化物基板の主面上への酸化物膜の形成およびイオン注入領域の形成
図２（Ｂ）を参照して、ＨＶＰＥ法により形成された単結晶である直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＧａＮ基板（ＩＩＩ族窒化物基板３０）のＮ原子表面である主面３０ｎ上に、スパッタ法により厚さ３００ｎｍのＴｉＯ2膜（酸化物膜２０ｂ）を形成させた。ここで、成長させるＴｉＯ2膜（酸化物膜２０ｂ）は、そのＮｂ（不純物）の濃度を、ＧａＮ基板（ＩＩＩ族窒化物基板３０）側から膜厚方向に、０．０１質量％から０．５質量％（例Ａ１）、０質量％から０．５質量％（例Ａ２）、０．０１質量％から５質量％（例Ａ３）、０．０１質量％から１０質量％（例Ａ４）と単調に変化させて、上記例Ａ１から例Ａ４の４種類とした。 2. Formation of Oxide Film on Main Surface of Group III Nitride Substrate and Formation of Ion Implanted Region Referring to FIG. 2B, a single crystal formed by HVPE method has a diameter of 2 inches (50.8 mm). Then, a 300 nm thick TiO 2 film (oxide film 20b) was formed on the main surface 30n, which is the N atom surface of the 500 μm thick GaN substrate (group III nitride substrate 30). Here, the TiO 2 film (oxide film 20b) to be grown has a concentration of Nb (impurities) of 0.01% by mass to 0.00% in the film thickness direction from the GaN substrate (group III nitride substrate 30) side. 5 wt% (Example A1), 0 wt% to 0.5 wt% (Example A2), 0.01 wt% to 5 wt% (Example A3), 0.01 wt% to 10 wt% (Example A4) Monotonous changes were made to the four types of Examples A1 to A4.

次いで、上記５種類のＴｉＯ2膜（酸化物膜２０ｂ）が形成されたＧａＮ基板（ＩＩＩ族窒化物基板３０）のＴｉＯ2膜（酸化物膜２０ｂ）側から水素イオンを注入して、ＧａＮ基板（ＩＩＩ族窒化物基板）のＮ原子表面である主面から３００ｎｍの深さの位置にイオン注入領域を形成した。 Next, hydrogen ions are implanted from the TiO 2 film (oxide film 20b) side of the GaN substrate (Group III nitride substrate 30) on which the five types of TiO 2 films (oxide film 20b) are formed, and the GaN substrate is obtained. An ion-implanted region was formed at a depth of 300 nm from the main surface which is the N atom surface of (Group III nitride substrate).

３．支持基板とＩＩＩ族窒化物基板との貼り合わせ
図２（Ｃ）を参照して、例Ａ１から例Ａ４のそれぞれにおいて、ＧａＮ支持基板（支持基板１０）に形成されたＴｉＯ2膜（酸化物膜２０ａ）と、イオン注入領域が形成されたＧａＮ基板（ＩＩＩ族窒化物基板）に形成されたＴｉＯ2膜（酸化物膜２０ｂ）とを、貼り合わせた。 3. Bonding of Support Substrate and Group III Nitride Substrate With reference to FIG. 2C, in each of Examples A1 to A4, a TiO 2 film (oxide film) formed on the GaN support substrate (support substrate 10) 20a) and a TiO 2 film (oxide film 20b) formed on the GaN substrate (group III nitride substrate) on which the ion implantation region was formed were bonded together.

４．ＩＩＩ族窒化物複合基板の形成
図２（Ｄ）を参照して、上記で貼り合わせた基板を、３００℃で２時間熱処理することにより、貼り合わせた基板の接合強度を高めるとともに、ＧａＮ基板（ＩＩＩ族窒化物基板）をイオン注入領域で分離することにより、例Ａ１〜例Ａ４について、ＧａＮ支持基板（支持基板１０）上にＴｉＯ2膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）を作製した。 4). Formation of Group III Nitride Composite Substrate Referring to FIG. 2D, the bonded substrate is heat-treated at 300 ° C. for 2 hours to increase the bonding strength of the bonded substrate and to increase the bonding strength of the GaN substrate ( By separating the group III nitride substrate) in the ion implantation region, for example A1 to example A4, a TiO 2 film (oxide film 20) and a GaN layer (group III nitride) on the GaN support substrate (support substrate 10). A GaN composite substrate (Group III nitride composite substrate 1) in which the layers 30a) were joined in this order was produced.

例Ａ１〜例Ａ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）は、ＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）の濃度が、ＴｉＯ2膜（酸化物膜２０）の支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向に、１質量％から０．０１質量％まで単調に変化し（例Ａ１）、１質量％から０質量％まで単調に変化し（例Ａ２）、１０質量％から０．０１質量％まで単調に変化し（例Ａ３）、１質量％から１０質量％を経て０．０１質量％まで極大値を有するように変化していた（例Ａ４）。 Example GaN composite substrate A1~ Example A4 (III-nitride composite substrate 1), the concentration of Nb (impurities) of the TiO 2 film (oxide film 20), the supporting substrate of the TiO 2 film (oxide film 20) It changes monotonically from 1% by mass to 0.01% by mass in the film thickness direction from the first main surface 20s on the 10 side to the second main surface 20t on the group III nitride layer 30a side (Example A1), 1% by mass. 1% to 0% by mass (Example A2), 10% to 0.01% by mass monotonically (Example A3), 1% to 10% by mass and 0.01% by mass maximum (Example A4).

５．ＩＩＩ族窒化物複合基板の物性
上記参考例Ａにおける接合強度の値を考慮すると、例Ａ１〜例Ａ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）におけるＴｉＯ2膜（酸化物膜２０）とＧａＮ支持基板（支持基板１０）との接合強度およびＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度は、それぞれ、１．４０および０．７８（例Ａ１）、１．４０および１．００（例Ａ２）、１．１０および０．７８（例Ａ３）、１．４０および０．７８（例Ａ４）と、いずれも高くなった。結果を表２に示した。 5. Physical Properties of Group III Nitride Composite Substrate Considering the bonding strength value in Reference Example A above, the TiO 2 film (oxide film 20) in GaN composite substrate (Group III nitride composite substrate 1) of Examples A1 to A4 and The bonding strength between the GaN supporting substrate (supporting substrate 10) and the bonding strength between the TiO 2 film (oxide film 20) and the GaN layer (Group III nitride layer 30a) are 1.40 and 0.78 (examples), respectively. A1), 1.40 and 1.00 (Example A2), 1.10 and 0.78 (Example A3), 1.40 and 0.78 (Example A4) were all high. The results are shown in Table 2.

また、例Ａ１〜例Ａ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向の比抵抗（電気抵抗率）は、ピコアンペアメータにより測定したところ、例Ａ１が２．８×１０2Ωｃｍ、例Ａ２が８．９×１０6Ωｃｍ、例Ａ３が６．５×１０-1Ωｃｍ、例Ａ４が８．７×１０1Ωｃｍあり、例Ａ２以外は高い導電性を示した。結果を表２に示した。例Ａ２のＧａＮ複合基板は、ＴｉＯ2膜（酸化物膜２０）のＧａＮ層（ＩＩＩ族窒化物層３０ａ）側の主面におけるＮｂ（不純物）の濃度が０質量％であったため、膜厚方向の導電性が極めて低くなったものと考えられる。また、例Ａ３のＧａＮ複合基板は、比抵抗が最も小さくなった。これは、ＴｉＯ2膜（酸化物膜２０）のＮｂ濃度が１０〜０．０１質量％でありＴｉＯ2膜全体としてのＮｂ濃度が高かったためと考えられる。 Moreover, when the specific resistance (electrical resistivity) in the film thickness maintaining direction of the GaN composite substrates (Group III nitride composite substrate 1) of Examples A1 to A4 was measured by a picoampere meter, Example A1 was 2.8 × 10. 2 Ωcm, Example A2 was 8.9 × 10 6 Ωcm, Example A3 was 6.5 × 10 −1 Ωcm, and Example A4 was 8.7 × 10 1 Ωcm. Except for Example A2, the samples exhibited high conductivity. The results are shown in Table 2. In the GaN composite substrate of Example A2, the Nb (impurity) concentration on the main surface of the TiO 2 film (oxide film 20) on the GaN layer (Group III nitride layer 30a) side was 0% by mass. It is considered that the electrical conductivity of the film was extremely low. Further, the specific resistance of the GaN composite substrate of Example A3 was the smallest. This is presumably because the Nb concentration of the TiO 2 film (oxide film 20) was 10 to 0.01% by mass and the Nb concentration of the entire TiO 2 film was high.

また、例Ａ１〜例Ａ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向のピーク波長が５００ｎｍの光の透過率は、紫外可視光透過率測定装置により測定したところ、例Ａ１が６２％、例Ａ２が８３％、例Ａ３が４６％、例Ａ４が４１％であった。結果を表２に示した。例Ａ２のＧａＮ複合基板は、光の透過率が最大であった。これは、ＴｉＯ2膜（酸化物膜２０）のＮｂ濃度が１〜０質量％と低かったためと考えられる。 Moreover, the transmittance | permeability of the light whose peak wavelength of the film thickness preservation | save direction of the GaN composite substrate (Group III nitride composite substrate 1) of Example A1-Example A4 is 500 nm was measured with the ultraviolet visible light transmittance | permeability measuring apparatus, Example A1 Was 62%, Example A2 was 83%, Example A3 was 46%, and Example A4 was 41%. The results are shown in Table 2. The GaN composite substrate of Example A2 had the highest light transmittance. This is presumably because the Nb concentration of the TiO 2 film (oxide film 20) was as low as 1 to 0% by mass.

Figure 2013084900
Figure 2013084900

（参考例Ｂ）
図１を参照して、多結晶（焼結体）で形成される直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＧａＮ支持基板（支持基板１０）、直径２インチ（５０．８ｍｍ）で厚さが６００ｎｍのＳｒＴｉＯ3膜（酸化物膜２０）および単結晶で形成される直径２インチ（５０．８ｍｍ）で厚さが３００ｎｍのＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、ＳｒＴｉＯ3膜（酸化物膜２０）中のＬａ（不純物）の濃度と、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ支持基板（支持基板１０）との接合強度との関係、ならびに、ＳｒＴｉＯ3膜（酸化物膜２０）中のＬａ（不純物）の濃度と、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度との関係を、以下のようにして調べた。 (Reference Example B)
Referring to FIG. 1, a GaN support substrate (support substrate 10) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm formed of polycrystal (sintered body), and a thickness of 2 inches (50.8 mm). A SrTiO 3 film having a thickness of 600 nm (oxide film 20) and a GaN layer (group III nitride layer 30a) having a diameter of 2 inches (50.8 mm) and a thickness of 300 nm formed of a single crystal are joined in this order. for GaN composite substrate (III-nitride composite substrate 1), SrTiO 3 film (oxide film 20) and the concentration of La (impurities) in, SrTiO 3 film (oxide film 20) and the GaN supporting substrate (supporting substrate 10 ) and the relationship between the bonding strength, as well as the concentration of SrTiO 3 film (La oxide film 20) in (impurity), SrTiO 3 film (oxide film 20) and the GaN layer (III-nitride layer 30a) With bonding strength The engagement, was examined in the following manner.

１．酸化物膜中の不純物の濃度と、酸化物膜と支持基板との接合強度と、の関係
酸化物膜２０としてＳｒＴｉＯ3膜を形成し、その不純物をＬａとしたこと以外は、参考例Ａと同様にして、５種類の積層基板１Ｓについてサンプルを作製し、引張試験によりそれらのサンプルの接合強度を測定した。いずれの積層基板１Ｓのいずれのサンプルも、ＧａＮ支持基板（支持基板）とＴｉＯ2膜（酸化物膜）との界面または界面の近傍で破断した。 1. Relationship between concentration of impurities in oxide film and bonding strength between oxide film and supporting substrate SrTiO 3 film was formed as the oxide film 20 and La was used as the impurity except Reference Example A. Similarly, samples were prepared for five types of laminated substrates 1S, and the bonding strength of these samples was measured by a tensile test. Any sample of any multilayer substrate 1S was broken at or near the interface between the GaN support substrate (support substrate) and the TiO 2 film (oxide film).

各種積層基板１Ｓの接合強度は、Ｌａ（不純物）の濃度が０質量％のとき１．００、Ｌａ（不純物）の濃度が０．０１質量％のとき１．０１、Ｌａ（不純物）の濃度が０．１質量％のとき１．０４、Ｌａ（不純物）の濃度が１質量％のとき１．４３、Ｌａ（不純物）の濃度が１０質量％のとき１．１２であった。すなわち、Ｌａ（不純物）の濃度が０質量％のときに比べて、Ｌａ（不純物）の濃度が０．０１質量％〜１０質量％のときは、ＳｒＴｉＯ3膜（酸化物膜）とＧａＮ支持基板（支持基板）との間の接合強度が高くなった。結果を表３にまとめた。 The bonding strength of the various laminated substrates 1S is 1.00 when the concentration of La (impurity) is 0 mass%, 1.01 when the concentration of La (impurity) is 0.01 mass%, and the concentration of La (impurity) is It was 1.04 when the concentration was 0.1% by mass, 1.43 when the concentration of La (impurity) was 1% by mass, and 1.12 when the concentration of La (impurity) was 10% by mass. That is, when the concentration of La (impurity) is 0.01% by mass to 10% by mass compared to when the concentration of La (impurity) is 0% by mass, the SrTiO 3 film (oxide film) and the GaN support substrate The bonding strength with the (support substrate) was increased. The results are summarized in Table 3.

２．酸化物膜中の不純物の濃度と、酸化物膜とＩＩＩ族窒化物層との接合強度と、の関係
酸化物膜２０としてＳｒＴｉＯ3膜を形成し、その不純物をＬａとしたこと以外は、参考例Ａと同様にして、５種類の積層基板１Ｔについてサンプルを作製し、引張試験によりそれらのサンプルの接合強度を測定した。いずれの積層基板１Ｔのいずれのサンプルも、ＧａＮ層（ＩＩＩ族窒化物層）とＴｉＯ2膜（酸化物膜）との界面または界面の近傍で破断した。 2. Relationship between the concentration of impurities in the oxide film and the bonding strength between the oxide film and the group III nitride layer Reference is made except that an SrTiO 3 film is formed as the oxide film 20 and the impurity is La. In the same manner as in Example A, samples were prepared for five types of laminated substrates 1T, and the bonding strength of these samples was measured by a tensile test. Any sample of any multilayer substrate 1T was broken at or near the interface between the GaN layer (group III nitride layer) and the TiO 2 film (oxide film).

各種積層基板１Ｔの接合強度は、Ｌａ（不純物）の濃度が０質量％のとき１．００、Ｌａ（不純物）の濃度が０．０１質量％のとき０．７６、Ｌａ（不純物）の濃度が０．１質量％のとき０．７１、Ｌａ（不純物）の濃度が１質量％のとき０．５５、Ｌａ（不純物）の濃度が１０質量％のとき０．５４であった。すなわち、Ｌａ（不純物）の濃度が０質量％のときに比べて、Ｌａ（不純物）の濃度が０．０１質量％から１０質量％と高くなる程、ＳｒＴｉＯ3膜（酸化物膜）とＧａＮ層（ＩＩＩ族窒化物層）との間の接合強度が低くなった。結果を表３にまとめた。 The bonding strength of various laminated substrates 1T is 1.00 when the concentration of La (impurity) is 0 mass%, 0.76 when the concentration of La (impurity) is 0.01 mass%, and the concentration of La (impurity) is It was 0.71 when the concentration was 0.1% by mass, 0.55 when the concentration of La (impurity) was 1% by mass, and 0.54 when the concentration of La (impurity) was 10% by mass. That is, the SrTiO 3 film (oxide film) and the GaN layer increase as the concentration of La (impurity) increases from 0.01% by mass to 10% by mass compared to when the concentration of La (impurity) is 0% by mass. The bonding strength with the (Group III nitride layer) was low. The results are summarized in Table 3.

Figure 2013084900
Figure 2013084900

図１および表３を参照して、ＧａＮ支持基板（支持基板１０）、ＳｒＴｉＯ3膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）において、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ支持基板（支持基板１０）との接合強度を高めるにはＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）濃度を高くすることが有効であり（特に、不純物濃度を１質量％程度とするのが好ましく）、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度を高めるにはＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）濃度を低くすることが有効であることがわかった。 Referring to FIG. 1 and Table 3, a GaN composite substrate (III) in which a GaN support substrate (support substrate 10), a SrTiO 3 film (oxide film 20), and a GaN layer (group III nitride layer 30a) are joined in this order. In the group nitride composite substrate 1), the La (impurity) concentration of the SrTiO 3 film (oxide film 20) is increased in order to increase the bonding strength between the SrTiO 3 film (oxide film 20) and the GaN support substrate (support substrate 10). Is effective (in particular, the impurity concentration is preferably about 1% by mass), and the bonding strength between the SrTiO 3 film (oxide film 20) and the GaN layer (group III nitride layer 30a) is increased. It has been found that it is effective to lower the La (impurity) concentration of the SrTiO 3 film (oxide film 20) in order to increase it.

（実施例Ｂ）
図１および図２を参照して、酸化物膜２０としてＳｒＴｉＯ3膜を形成し、その不純物をＬａとしたこと以外は、実施例Ａと同様にして、例Ｂ１〜例Ｂ４として、ＧａＮ支持基板（支持基板１０）上にＳｒＴｉＯ3膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）を作製した。 (Example B)
Referring to FIGS. 1 and 2, as Example B1 to Example B4, a GaN support substrate is formed in the same manner as Example A, except that an SrTiO 3 film is formed as oxide film 20 and its impurity is La. A GaN composite substrate (Group III nitride composite substrate 1) in which the SrTiO 3 film (oxide film 20) and the GaN layer (Group III nitride layer 30a) were joined in this order on the (support substrate 10) was produced.

例Ｂ１〜例Ｂ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）は、ＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）の濃度が、ＳｒＴｉＯ3膜（酸化物膜２０）の支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向に、１質量％から０．０１質量％まで単調に変化し（例Ｂ１）、１質量％から０質量％まで単調に変化し（例Ｂ２）、１０質量％から０．０１質量％まで単調に変化し（例Ｂ３）、１質量％から１０質量％を経て０．０１質量％まで極大値を有するように変化していた（例Ｂ４）。 Example GaN composite substrate B1~ Example B4 (III-nitride composite substrate 1), the concentration of La (impurities) of SrTiO 3 film (oxide film 20), the supporting substrate of SrTiO 3 film (oxide film 20) It changes monotonically from 1% by mass to 0.01% by mass in the film thickness direction from the first main surface 20s on the 10 side to the second main surface 20t on the group III nitride layer 30a side (Example B1), 1% by mass. 1% to 0% by mass (Example B2), 10% to 0.01% by mass monotonically (Example B3), from 1% to 10% by mass to 0.01% by mass maximum (Example B4).

例Ｂ１〜例Ｂ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、上記参考例Ｂにおける接合強度の値を考慮すると、例Ｂ１〜例Ｂ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）におけるＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ支持基板（支持基板１０）との接合強度およびＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度は、それぞれ、１．４３および０．７６（例Ｂ１）、１．４３および１．００（例Ｂ２）、１．１２および０．７６（例Ｂ３）、１．４３および０．７６（例Ｂ４）と、いずれも高くなった。結果を表４に示した。 Regarding the GaN composite substrates of Examples B1 to B4 (Group III nitride composite substrate 1), considering the bonding strength values in Reference Example B above, the GaN composite substrates of Examples B1 to B4 (Group III nitride composite substrate 1) The bonding strength between the SrTiO 3 film (oxide film 20) and the GaN supporting substrate (supporting substrate 10) and the bonding strength between the SrTiO 3 film (oxide film 20) and the GaN layer (Group III nitride layer 30a) in FIG. 1.43 and 0.76 (Example B1), 1.43 and 1.00 (Example B2), 1.12 and 0.76 (Example B3), 1.43 and 0.76 (Example B4), respectively. Both were high. The results are shown in Table 4.

また、例Ｂ１〜例Ｂ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向の比抵抗（電気抵抗率）は、例Ｂ１が９．１×１０2Ωｃｍ、例Ｂ２が４．７×１０7Ωｃｍ、例Ｂ３が１．３×１０0Ωｃｍ、例Ｂ４が３．８×１０2Ωｃｍであり、例Ｂ２以外は高い導電性を示した。結果を表４に示した。例Ｂ２のＧａＮ複合基板は、ＳｒＴｉＯ3膜（酸化物膜２０）のＧａＮ層（ＩＩＩ族窒化物層３０ａ）側の主面におけるＬａ（不純物）の濃度が０質量％であったため、膜厚方向の導電性が極めて低くなったものと考えられる。また、例Ｂ３のＧａＮ複合基板は、比抵抗が最も小さくなった。これは、ＳｒＴｉＯ3膜（酸化物膜２０）のＬａ濃度が１０〜０．０１質量％でありＳｒＴｉＯ3膜全体としてのＬａ濃度が高かったためと考えられる。 The specific resistance (electrical resistivity) in the film thickness maintaining direction of the GaN composite substrates (Group III nitride composite substrate 1) of Examples B1 to B4 is 9.1 × 10 2 Ωcm in Example B1, and 4. in Example B2. 7 × 10 7 Ωcm, Example B3 was 1.3 × 10 0 Ωcm, and Example B4 was 3.8 × 10 2 Ωcm. Except for Example B2, high conductivity was exhibited. The results are shown in Table 4. In the GaN composite substrate of Example B2, the La (impurity) concentration on the main surface of the SrTiO 3 film (oxide film 20) on the GaN layer (Group III nitride layer 30a) side was 0% by mass. It is considered that the electrical conductivity of the film was extremely low. In addition, the specific resistance of the GaN composite substrate of Example B3 was the smallest. This is presumably because the La concentration of the SrTiO 3 film (oxide film 20) was 10 to 0.01% by mass and the La concentration of the entire SrTiO 3 film was high.

また、例Ｂ１〜例Ｂ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向のピーク波長が５００ｎｍの光の透過率は、例Ｂ１が６４％、例Ｂ２が８６％、例Ｂ３が４８％、例Ｂ４が４３％であった。結果を表４に示した。例Ｂ２のＧａＮ複合基板は、光の透過率が最大であった。これは、ＳｒＴｉＯ3膜（酸化物膜２０）のＬａ濃度が１〜０質量％と低かったためと考えられる。 Moreover, the transmittance | permeability of the light whose peak wavelength of the film thickness maintenance direction of the GaN composite substrate (Group III nitride composite substrate 1) of Example B1 to Example B4 is 500 nm is 64% for Example B1, 86% for Example B2, and Example B3. Was 48% and Example B4 was 43%. The results are shown in Table 4. The GaN composite substrate of Example B2 had the highest light transmittance. This is presumably because the La concentration of the SrTiO 3 film (oxide film 20) was as low as 1 to 0% by mass.

Figure 2013084900
Figure 2013084900

（参考例Ｃ）
図１を参照して、多結晶（焼結体）で形成される直径２インチ（５０．８ｍｍ）で厚さ５００μｍのムライト支持基板（支持基板１０）、直径２インチ（５０．８ｍｍ）で厚さが６００ｎｍのＴｉＯ2膜（酸化物膜２０）および単結晶で形成される直径２インチ（５０．８ｍｍ）で厚さが３００ｎｍのＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、ＴｉＯ2膜（酸化物膜２０）中のＮｂ（不純物）の濃度と、ＴｉＯ2膜（酸化物膜２０）とムライト支持基板（支持基板１０）との接合強度との関係、ならびに、ＴｉＯ2膜（酸化物膜２０）中のＮｂ（不純物）の濃度と、ＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度との関係を、以下のようにして調べた。 (Reference Example C)
Referring to FIG. 1, a mullite supporting substrate (supporting substrate 10) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm formed of polycrystal (sintered body), and a thickness of 2 inches (50.8 mm). A TiO 2 film (oxide film 20) having a thickness of 600 nm and a GaN layer (group III nitride layer 30a) having a diameter of 2 inches (50.8 mm) and a thickness of 300 nm formed of a single crystal are joined in this order. for GaN composite substrate (III-nitride composite substrate 1), and the concentration of Nb (impurities) in the TiO 2 film (oxide film 20), a TiO 2 film (oxide film 20) and the mullite support substrate (support substrate 10 ) relationship between the bonding strength between, and the concentration of Nb (impurities) in the TiO 2 film (oxide film 20), a TiO 2 film (oxide film 20) and the GaN layer (III-nitride layer 30a) The relationship between bonding strength and It was examined in to.

１．酸化物膜中の不純物の濃度と、酸化物膜と支持基板との接合強度と、の関係
支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのムライト支持基板を用いたこと以外は、参考例Ａと同様にして、５種類の積層基板１Ｓについてサンプルを作製し、引張試験によりそれらのサンプルの接合強度を測定した。いずれの積層基板１Ｓのいずれのサンプルも、ムライト支持基板（支持基板）とＴｉＯ2膜（酸化物膜）との界面または界面の近傍で破断した。 1. Relationship between impurity concentration in oxide film and bonding strength between oxide film and supporting substrate Except that a mullite supporting substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm was used as the supporting substrate 10. In the same manner as in Reference Example A, samples were prepared for five types of laminated substrates 1S, and the bonding strength of these samples was measured by a tensile test. Any sample of any laminated substrate 1S was broken at or near the interface between the mullite support substrate (support substrate) and the TiO 2 film (oxide film).

各種積層基板１Ｓの接合強度は、Ｎｂ（不純物）の濃度が０質量％のとき１．００、Ｎｂ（不純物）の濃度が０．０１質量％のとき１．２１、Ｎｂ（不純物）の濃度が０．１質量％のとき１．２２、Ｎｂ（不純物）の濃度が１質量％のとき１．６８、Ｎｂ（不純物）の濃度が１０質量％のとき１．３２であった。すなわち、Ｎｂ（不純物）の濃度が０質量％のときに比べて、Ｎｂ（不純物）の濃度が０．０１質量％〜１０質量％のときは、ＴｉＯ2膜（酸化物膜）とムライト支持基板（支持基板）との間の接合強度が高くなった。結果を表５にまとめた。 The bonding strength of the various laminated substrates 1S is 1.00 when the concentration of Nb (impurity) is 0% by mass, 1.21 when the concentration of Nb (impurity) is 0.01% by mass, and the concentration of Nb (impurity) is It was 1.22 when the concentration was 0.1% by mass, 1.68 when the concentration of Nb (impurity) was 1% by mass, and 1.32 when the concentration of Nb (impurity) was 10% by mass. That is, when the concentration of Nb (impurity) is 0.01% by mass to 10% by mass compared to when the concentration of Nb (impurity) is 0% by mass, the TiO 2 film (oxide film) and the mullite supporting substrate The bonding strength with the (support substrate) was increased. The results are summarized in Table 5.

２．酸化物膜中の不純物の濃度と、酸化物膜とＩＩＩ族窒化物層との接合強度と、の関係
参考例Ａにおけるサンプルの接合強度の測定から、各種積層基板１Ｔの接合強度は、Ｎｂ（不純物）の濃度が０質量％のとき１．００、Ｎｂ（不純物）の濃度が０．０１質量％のとき０．７８、Ｎｂ（不純物）の濃度が０．１質量％のとき０．７２、Ｌａ（不純物）の濃度が１質量％のとき０．５６、Ｌａ（不純物）の濃度が１０質量％のとき０．５５であった。すなわち、Ｌａ（不純物）の濃度が０質量％のときに比べて、Ｌａ（不純物）の濃度が０．０１質量％から１０質量％と高くなる程、ＴｉＯ2膜（酸化物膜）とＧａＮ層（ＩＩＩ族窒化物膜）との間の接合強度が低くなった。結果を表５にまとめた。 2. Relationship between the concentration of impurities in the oxide film and the bonding strength between the oxide film and the group III nitride layer From the measurement of the bonding strength of the sample in Reference Example A, the bonding strength of the various laminated substrates 1T is Nb ( 1.00 when the concentration of (impurity) is 0% by mass, 0.78 when the concentration of Nb (impurity) is 0.01% by mass, 0.72 when the concentration of Nb (impurity) is 0.1% by mass, It was 0.56 when the concentration of La (impurity) was 1% by mass, and 0.55 when the concentration of La (impurity) was 10% by mass. That is, the TiO 2 film (oxide film) and the GaN layer increase as the concentration of La (impurity) increases from 0.01% by mass to 10% by mass compared to the case where the concentration of La (impurity) is 0% by mass. The bonding strength with (Group III nitride film) was low. The results are summarized in Table 5.

Figure 2013084900
Figure 2013084900

図１および表５を参照して、ムライト支持基板（支持基板１０）、ＴｉＯ2膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）において、ＴｉＯ2膜（酸化物膜２０）とムライト支持基板（支持基板１０）との接合強度を高めるにはＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）濃度を高くすることが有効であり（特に、不純物濃度を１質量％程度とするのが好ましく）、ＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度を高めるにはＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）濃度を低くすることが有効であることがわかった。 Referring to FIG. 1 and Table 5, a GaN composite substrate (III) in which a mullite support substrate (support substrate 10), a TiO 2 film (oxide film 20), and a GaN layer (group III nitride layer 30a) are joined in this order. In the group nitride composite substrate 1), in order to increase the bonding strength between the TiO 2 film (oxide film 20) and the mullite support substrate (support substrate 10), the Nb (impurity) concentration of the TiO 2 film (oxide film 20) Is effective (especially, the impurity concentration is preferably about 1% by mass), and the bonding strength between the TiO 2 film (oxide film 20) and the GaN layer (group III nitride layer 30a) is increased. It has been found that it is effective to lower the Nb (impurity) concentration of the TiO 2 film (oxide film 20) in order to increase it.

（実施例Ｃ）
図１および図２を参照して、支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのムライト支持基板を用いたこと以外は、実施例Ａと同様にして、例Ｃ１〜例Ｃ４として、ムライト支持基板（支持基板１０）上にＴｉＯ2膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）を作製した。 (Example C)
1 and 2, Example C1 to Example C4 are the same as Example A except that a mullite support substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm is used as the support substrate 10. A GaN composite substrate (Group III nitride composite substrate 1) in which a TiO 2 film (oxide film 20) and a GaN layer (Group III nitride layer 30a) are joined in this order on a mullite support substrate (support substrate 10). Was made.

例Ｃ１〜例Ｃ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）は、ＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）の濃度が、ＴｉＯ2膜（酸化物膜２０）の支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向に、１質量％から０．０１質量％まで単調に変化し（例Ｃ１）、１質量％から０質量％まで単調に変化し（例Ｃ２）、１０質量％から０．０１質量％まで単調に変化し（例Ｃ３）、１質量％から１０質量％を経て０．０１質量％まで極大値を有するように変化していた（例Ｃ４）。 Example GaN composite substrate C1~ Example C4 (III-nitride composite substrate 1), the concentration of Nb (impurities) of the TiO 2 film (oxide film 20), the supporting substrate of the TiO 2 film (oxide film 20) It changes monotonically from 1% by mass to 0.01% by mass in the film thickness direction from the first main surface 20s on the 10 side to the second main surface 20t on the side of the group III nitride layer 30a (Example C1), 1% by mass. 1% to 0% by mass (Example C2), 10% to 0.01% by mass monotonically (Example C3), 1% to 10% by mass and 0.01% by mass maximum (Example C4).

例Ｃ１〜例Ｃ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、上記参考例Ｃにおける接合強度の値を考慮すると、例Ｃ１〜例Ｃ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）におけるＴｉＯ2膜（酸化物膜２０）とムライト支持基板（支持基板１０）との接合強度およびＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度は、それぞれ、１．６８および０．７８（例Ｃ１）、１．６８および１．００（例Ｃ２）、１．３２および０．７８（例Ｃ３）、１．６８および０．７８（例Ｃ４）と、いずれも高くなった。結果を表６に示した。 Regarding the GaN composite substrates of Examples C1 to C4 (Group III nitride composite substrate 1), considering the bonding strength values in Reference Example C above, the GaN composite substrates of Examples C1 to C4 (Group III nitride composite substrate 1) The bonding strength between the TiO 2 film (oxide film 20) and the mullite supporting substrate (supporting substrate 10) and the bonding strength between the TiO 2 film (oxide film 20) and the GaN layer (group III nitride layer 30a) in FIG. 1.68 and 0.78 (Example C1), 1.68 and 1.00 (Example C2), 1.32 and 0.78 (Example C3), 1.68 and 0.78 (Example C4), respectively. Both were high. The results are shown in Table 6.

また、例Ｃ１〜例Ｃ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向のピーク波長が５００ｎｍの光の透過率は、例Ｃ１が５６％、例Ｃ２が７５％、例Ｃ３が４１％、例Ｃ４が３７％であった。結果を表６に示した。例Ｃ２のＧａＮ複合基板は、光の透過率が最大であった。これは、ＴｉＯ2膜（酸化物膜２０）のＮｂ濃度が１〜０質量％と低かったためと考えられる。 Moreover, the transmittance | permeability of the light whose peak wavelength of the film thickness maintenance direction of the GaN composite substrate (Group III nitride composite substrate 1) of Examples C1-C4 is 500 nm is 56% for Example C1, 75% for Example C2, and Example C3. Was 41% and Example C4 was 37%. The results are shown in Table 6. The GaN composite substrate of Example C2 had the highest light transmittance. This is presumably because the Nb concentration of the TiO 2 film (oxide film 20) was as low as 1 to 0% by mass.

Figure 2013084900
Figure 2013084900

（参考例Ｄ）
図１を参照して、多結晶（焼結体）で形成される直径２インチ（５０．８ｍｍ）で厚さ５００μｍのムライト支持基板（支持基板１０）、直径２インチ（５０．８ｍｍ）で厚さが６００ｎｍのＳｒＴｉＯ3膜（酸化物膜２０）および単結晶で形成される直径２インチ（５０．８ｍｍ）で厚さが３００ｎｍのＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、ＳｒＴｉＯ3膜（酸化物膜２０）中のＬａ（不純物）の濃度と、ＳｒＴｉＯ3膜（酸化物膜２０）とムライト支持基板（支持基板１０）との接合強度との関係、ならびに、ＳｒＴｉＯ3膜（酸化物膜２０）中のＬａ（不純物）の濃度と、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度との関係を、以下のようにして調べた。 (Reference Example D)
Referring to FIG. 1, a mullite supporting substrate (supporting substrate 10) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm formed of polycrystal (sintered body), and a thickness of 2 inches (50.8 mm). A SrTiO 3 film having a thickness of 600 nm (oxide film 20) and a GaN layer (group III nitride layer 30a) having a diameter of 2 inches (50.8 mm) and a thickness of 300 nm formed of a single crystal are joined in this order. for GaN composite substrate (III-nitride composite substrate 1), SrTiO 3 film and the concentration of La (impurities) of (oxide film 20) in, SrTiO 3 film (oxide film 20) and the mullite support substrate (support substrate 10 ) and the relationship between the bonding strength, as well as the concentration of SrTiO 3 film (La oxide film 20) in (impurity), SrTiO 3 film (oxide film 20) and the GaN layer (III-nitride layer 30a) Bonding strength with The relationship was examined in the following manner.

１．酸化物膜中の不純物の濃度と、酸化物膜と支持基板との接合強度と、の関係
支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのムライト支持基板を用いたこと以外は、参考例Ｂと同様にして、５種類の積層基板１Ｓについてサンプルを作製し、引張試験によりそれらのサンプルの接合強度を測定した。いずれの積層基板１Ｓのいずれのサンプルも、ムライト支持基板（支持基板）とＴｉＯ2膜（酸化物膜）との界面または界面の近傍で破断した。 1. Relationship between impurity concentration in oxide film and bonding strength between oxide film and supporting substrate Except that a mullite supporting substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm was used as the supporting substrate 10. In the same manner as in Reference Example B, samples were prepared for five types of laminated substrates 1S, and the bonding strength of these samples was measured by a tensile test. Any sample of any laminated substrate 1S was broken at or near the interface between the mullite support substrate (support substrate) and the TiO 2 film (oxide film).

各種積層基板１Ｓの接合強度は、Ｌａ（不純物）の濃度が０質量％のとき１．００、Ｌａ（不純物）の濃度が０．０１質量％のとき１．２１、Ｌａ（不純物）の濃度が０．１質量％のとき１．２５、Ｌａ（不純物）の濃度が１質量％のとき１．７２、Ｌａ（不純物）の濃度が１０質量％のとき１．３４であった。すなわち、Ｌａ（不純物）の濃度が０質量％のときに比べて、Ｌａ（不純物）の濃度が０．０１質量％〜１０質量％のときは、ＧａＮ支持基板（支持基板）とＳｒＴｉＯ3膜（酸化物膜）との間の接合強度が高くなった。結果を表７にまとめた。 The bonding strength of the various laminated substrates 1S is 1.00 when the concentration of La (impurity) is 0 mass%, 1.21 when the concentration of La (impurity) is 0.01 mass%, and the concentration of La (impurity) is It was 1.25 when the concentration was 0.1% by mass, 1.72 when the concentration of La (impurity) was 1% by mass, and 1.34 when the concentration of La (impurity) was 10% by mass. That is, when the concentration of La (impurity) is 0.01% by mass to 10% by mass, compared to when the concentration of La (impurity) is 0% by mass, the GaN support substrate (support substrate) and the SrTiO 3 film ( The bonding strength between the oxide film and the oxide film increased. The results are summarized in Table 7.

２．酸化物膜中の不純物の濃度と、酸化物膜とＩＩＩ族窒化物層との接合強度と、の関係
参考例Ｂにおけるサンプルの接合強度の測定から、各種積層基板１Ｔの接合強度は、Ｌａ（不純物）の濃度が０質量％のとき１．００、Ｌａ（不純物）の濃度が０．０１質量％のとき０．７６、Ｌａ（不純物）の濃度が０．１質量％のとき０．７１、Ｌａ（不純物）の濃度が１質量％のとき０．５５、Ｌａ（不純物）の濃度が１０質量％のとき０．５４であった。すなわち、Ｌａ（不純物）の濃度が０質量％のときに比べて、Ｌａ（不純物）の濃度が０．０１質量％から１０質量％と高くなる程、ＳｒＴｉＯ3膜（酸化物膜）とＧａＮ支持基板（支持基板）との間の接合強度が低くなった。結果を表７にまとめた。 2. Relationship between the concentration of impurities in the oxide film and the bonding strength between the oxide film and the group III nitride layer From the measurement of the bonding strength of the sample in Reference Example B, the bonding strength of the various laminated substrates 1T is La ( 1.00 when the concentration of (impurity) is 0% by mass, 0.76 when the concentration of La (impurity) is 0.01% by mass, 0.71 when the concentration of La (impurity) is 0.1% by mass, It was 0.55 when the concentration of La (impurity) was 1% by mass, and 0.54 when the concentration of La (impurity) was 10% by mass. That is, the SrTiO 3 film (oxide film) and the GaN support are increased as the concentration of La (impurity) is increased from 0.01% by mass to 10% by mass compared to the case where the concentration of La (impurity) is 0% by mass. Bonding strength with the substrate (support substrate) was lowered. The results are summarized in Table 7.

Figure 2013084900
Figure 2013084900

図１および表７を参照して、ムライト支持基板（支持基板１０）、ＳｒＴｉＯ3膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）において、ＳｒＴｉＯ3膜（酸化物膜２０）とムライト支持基板（支持基板１０）との接合強度を高めるにはＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）濃度を高くすることが有効であり（特に、不純物濃度を１質量％程度とするのが好ましく）、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度を高めるにはＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）濃度を低くすることが有効であることがわかった。 Referring to FIG. 1 and Table 7, a GaN composite substrate (III) in which a mullite support substrate (support substrate 10), a SrTiO 3 film (oxide film 20), and a GaN layer (group III nitride layer 30a) are joined in this order. In the group nitride composite substrate 1), in order to increase the bonding strength between the SrTiO 3 film (oxide film 20) and the mullite support substrate (support substrate 10), the La (impurity) concentration of the SrTiO 3 film (oxide film 20) Is effective (in particular, the impurity concentration is preferably about 1% by mass), and the bonding strength between the SrTiO 3 film (oxide film 20) and the GaN layer (group III nitride layer 30a) is increased. It has been found that it is effective to lower the La (impurity) concentration of the SrTiO 3 film (oxide film 20) in order to increase it.

（実施例Ｄ）
図１および図２を参照して、支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのムライト支持基板を用いたこと以外は、実施例Ｂと同様にして、例Ｄ１〜例Ｄ４として、ムライト支持基板（支持基板１０）上にＳｒＴｉＯ3膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）を作製した。 (Example D)
1 and 2, Example D1 to Example D4 are the same as Example B except that a mullite support substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm is used as the support substrate 10. A GaN composite substrate (Group III nitride composite substrate 1) in which a SrTiO 3 film (oxide film 20) and a GaN layer (Group III nitride layer 30a) are joined in this order on a mullite support substrate (support substrate 10). Was made.

例Ｄ１〜例Ｄ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）は、ＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）の濃度が、ＳｒＴｉＯ3膜（酸化物膜２０）の支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向に、１質量％から０．０１質量％まで単調に変化し（例Ｄ１）、１質量％から０質量％まで単調に変化し（例Ｄ２）、１０質量％から０．０１質量％まで単調に変化し（例Ｄ３）、１質量％から１０質量％を経て０．０１質量％まで極大値を有するように変化していた（例Ｄ４）。 GaN composite substrate Example D1~ Example D4 (III-nitride composite substrate 1), the concentration of La (impurities) of SrTiO 3 film (oxide film 20), the supporting substrate of SrTiO 3 film (oxide film 20) It changes monotonically from 1% by mass to 0.01% by mass in the film thickness direction from the first main surface 20s on the 10th side to the second main surface 20t on the III-nitride layer 30a side (Example D1), 1% by mass 1% to 0% by mass (Example D2), 10% to 0.01% by mass monotonically (Example D3), 1% to 10% by mass and 0.01% by mass maximum (Example D4).

例Ｄ１〜例Ｄ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、上記参考例Ｄにおける接合強度の値を考慮すると、例Ｄ１〜例Ｄ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）におけるＳｒＴｉＯ3膜（酸化物膜２０）とムライト支持基板（支持基板１０）との接合強度およびＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度は、それぞれ、１．７２および０．７６（例Ｄ１）、１．７２および１．００（例Ｄ２）、１．３４および０．７６（例Ｄ３）、１．７２および０．７６（例Ｄ４）と、いずれも高くなった。結果を表８に示した。 For the GaN composite substrates (Group III nitride composite substrate 1) of Examples D1 to D4, considering the bonding strength values in Reference Example D above, the GaN composite substrates of Examples D1 to D4 (Group III nitride composite substrate 1) The bonding strength between the SrTiO 3 film (oxide film 20) and the mullite supporting substrate (supporting substrate 10) and the bonding strength between the SrTiO 3 film (oxide film 20) and the GaN layer (group III nitride layer 30a) in FIG. 1.72 and 0.76 (Example D1), 1.72 and 1.00 (Example D2), 1.34 and 0.76 (Example D3), 1.72 and 0.76 (Example D4), respectively. Both were high. The results are shown in Table 8.

また、例Ｄ１〜例Ｄ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向のピーク波長が５００ｎｍの光の透過率は、例Ｄ１が５８％、例Ｄ２が７７％、例Ｄ３が４３％、例Ｄ４が３９％であった。結果を表８に示した。例Ｄ２のＧａＮ複合基板は、光の透過率が最大であった。これは、ＳｒＴｉＯ3膜（酸化物膜２０）のＬａ濃度が１〜０質量％と低かったためと考えられる。 Moreover, the transmittance | permeability of the light whose peak wavelength of the film thickness maintenance direction of the GaN composite substrate (Group III nitride composite substrate 1) of Example D1-Example D4 is 500 nm is 58% in Example D1, 77% in Example D2, and Example D3. Was 43% and Example D4 was 39%. The results are shown in Table 8. The GaN composite substrate of Example D2 had the highest light transmittance. This is presumably because the La concentration of the SrTiO 3 film (oxide film 20) was as low as 1 to 0% by mass.

Figure 2013084900
Figure 2013084900

（参考例Ｅ）
図１を参照して、多結晶で形成される直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＭｏ支持基板（支持基板１０）、直径２インチ（５０．８ｍｍ）で厚さが６００ｎｍのＴｉＯ2膜（酸化物膜２０）および単結晶で形成される直径２インチ（５０．８ｍｍ）で厚さが３００ｎｍのＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、ＴｉＯ2膜（酸化物膜２０）中のＮｂ（不純物）の濃度と、ＴｉＯ2膜（酸化物膜２０）とＭｏ支持基板（支持基板１０）との接合強度との関係、ならびに、ＴｉＯ2膜（酸化物膜２０）中のＮｂ（不純物）の濃度と、ＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度との関係を、以下のようにして調べた。 (Reference Example E)
Referring to FIG. 1, a Mo support substrate (support substrate 10) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm and TiO 2 having a diameter of 2 inches (50.8 mm) and a thickness of 600 nm are formed of polycrystal. Two films (oxide film 20) and a GaN composite substrate (III nitride layer 30a) having a diameter of 2 inches (50.8 mm) and a thickness of 300 nm formed of a single crystal are joined in this order (III bonding strength of the nitride composite substrate 1), and the concentration of the TiO 2 film (Nb oxide film 20) in (impurities), and Mo support substrate and the TiO 2 film (oxide film 20) (supporting substrate 10) relationship, as well as the bonding strength and the concentration of Nb (impurities) in the TiO 2 film (oxide film 20), a TiO 2 film (oxide film 20) and the GaN layer and the (III-nitride layer 30a) The relationship was investigated as follows.

１．酸化物膜中の不純物の濃度と、酸化物膜と支持基板との接合強度と、の関係
支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＭｏ支持基板を用いたこと以外は、参考例Ａと同様にして、５種類の積層基板１Ｓについてサンプルを作製し、引張試験によりそれらのサンプルの接合強度を測定した。いずれの積層基板１Ｓのいずれのサンプルも、Ｍｏ支持基板（支持基板）とＴｉＯ2膜（酸化物膜）との界面または界面の近傍で破断した。 1. Relationship between impurity concentration in oxide film and bonding strength between oxide film and supporting substrate Except that a Mo supporting substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm was used as the supporting substrate 10. In the same manner as in Reference Example A, samples were prepared for five types of laminated substrates 1S, and the bonding strength of these samples was measured by a tensile test. Any sample of any laminated substrate 1S was broken at or near the interface between the Mo support substrate (support substrate) and the TiO 2 film (oxide film).

各種積層基板１Ｓの接合強度は、Ｎｂ（不純物）の濃度が０質量％のとき１．００、Ｎｂ（不純物）の濃度が０．０１質量％のとき１．１１、Ｎｂ（不純物）の濃度が０．１質量％のとき１．１２、Ｎｂ（不純物）の濃度が１質量％のとき１．５４、Ｎｂ（不純物）の濃度が１０質量％のとき１．２１であった。すなわち、Ｎｂ（不純物）の濃度が０質量％のときに比べて、Ｎｂ（不純物）の濃度が０．０１質量％〜１０質量％のときは、ＴｉＯ2膜（酸化物膜）とＭｏ支持基板（支持基板）との間の接合強度が高くなった。結果を表９にまとめた。 The bonding strength of the various laminated substrates 1S is 1.00 when the Nb (impurity) concentration is 0 mass%, 1.11 when the Nb (impurity) concentration is 0.01 mass%, and the Nb (impurity) concentration is 1. It was 1.12 when the concentration was 0.1% by mass, 1.54 when the concentration of Nb (impurity) was 1% by mass, and 1.21 when the concentration of Nb (impurity) was 10% by mass. That is, when the concentration of Nb (impurity) is 0.01% by mass to 10% by mass compared to when the concentration of Nb (impurity) is 0% by mass, the TiO 2 film (oxide film) and the Mo support substrate The bonding strength with the (support substrate) was increased. The results are summarized in Table 9.

２．酸化物膜中の不純物の濃度と、酸化物膜とＩＩＩ族窒化物層との接合強度と、の関係
参考例Ａにおけるサンプルの接合強度の測定から、各種積層基板１Ｔの接合強度は、Ｎｂ（不純物）の濃度が０質量％のとき１．００、Ｎｂ（不純物）の濃度が０．０１質量％のとき０．７８、Ｎｂ（不純物）の濃度が０．１質量％のとき０．７２、Ｌａ（不純物）の濃度が１質量％のとき０．５６、Ｌａ（不純物）の濃度が１０質量％のとき０．５５であった。すなわち、Ｎｂ（不純物）の濃度が０質量％のときに比べて、Ｎｂ（不純物）の濃度が０．０１質量％から１０質量％と高くなる程、ＴｉＯ2膜（酸化物膜）とＧａＮ層（ＩＩＩ族窒化物膜）との間の接合強度が低くなった。結果を表９にまとめた。 2. Relationship between the concentration of impurities in the oxide film and the bonding strength between the oxide film and the group III nitride layer From the measurement of the bonding strength of the sample in Reference Example A, the bonding strength of the various laminated substrates 1T is Nb ( 1.00 when the concentration of (impurity) is 0% by mass, 0.78 when the concentration of Nb (impurity) is 0.01% by mass, 0.72 when the concentration of Nb (impurity) is 0.1% by mass, It was 0.56 when the concentration of La (impurity) was 1% by mass, and 0.55 when the concentration of La (impurity) was 10% by mass. That is, as the Nb (impurity) concentration increases from 0.01% by mass to 10% by mass compared to when the Nb (impurity) concentration is 0% by mass, the TiO 2 film (oxide film) and the GaN layer The bonding strength with (Group III nitride film) was low. The results are summarized in Table 9.

Figure 2013084900
Figure 2013084900

図１および表９を参照して、Ｍｏ支持基板（支持基板１０）、ＴｉＯ2膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）において、ＴｉＯ2膜（酸化物膜２０）とＭｏ支持基板（支持基板１０）との接合強度を高めるにはＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）濃度を高くすることが有効であり（特に、不純物濃度を１質量％程度とするのが好ましく）、ＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度を高めるにはＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）濃度を低くすることが有効であることがわかった。 Referring to FIG. 1 and Table 9, a GaN composite substrate (III) in which a Mo support substrate (support substrate 10), a TiO 2 film (oxide film 20), and a GaN layer (group III nitride layer 30a) are joined in this order. In the group nitride composite substrate 1), the Nb (impurity) concentration of the TiO 2 film (oxide film 20) is increased in order to increase the bonding strength between the TiO 2 film (oxide film 20) and the Mo support substrate (support substrate 10). Is effective (especially, the impurity concentration is preferably about 1% by mass), and the bonding strength between the TiO 2 film (oxide film 20) and the GaN layer (group III nitride layer 30a) is increased. It has been found that it is effective to lower the Nb (impurity) concentration of the TiO 2 film (oxide film 20) in order to increase it.

（実施例Ｅ）
図１および図２を参照して、支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＭｏ支持基板を用いたこと以外は、実施例Ａと同様にして、例Ｅ１〜例Ｅ４として、Ｍｏ支持基板（支持基板１０）上にＴｉＯ2膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）を作製した。 (Example E)
1 and 2, Examples E1 to E4 are the same as Example A except that a Mo support substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm is used as the support substrate 10. A GaN composite substrate (group III nitride composite substrate 1) in which a TiO 2 film (oxide film 20) and a GaN layer (group III nitride layer 30a) are joined in this order on a Mo support substrate (support substrate 10). Was made.

例Ｅ１〜例Ｅ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）は、ＴｉＯ2膜（酸化物膜２０）のＮｂ（不純物）の濃度が、ＴｉＯ2膜（酸化物膜２０）の支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向に、１質量％から０．０１質量％まで単調に変化し（例Ｅ１）、１質量％から０質量％まで単調に変化し（例Ｅ２）、１０質量％から０．０１質量％まで単調に変化し（例Ｅ３）、１質量％から１０質量％を経て０．０１質量％まで極大値を有するように変化していた（例Ｅ４）。 Example GaN composite substrate E1~ Example E4 (III-nitride composite substrate 1), the concentration of Nb (impurities) of the TiO 2 film (oxide film 20), the supporting substrate of the TiO 2 film (oxide film 20) It changes monotonically from 1% by mass to 0.01% by mass in the film thickness direction from the first main surface 20s on the 10 side to the second main surface 20t on the side of the group III nitride layer 30a (Example E1), 1% by mass. 1% to 0% by mass (Example E2), 10% to 0.01% by mass monotonically (Example E3), 1% to 10% by mass and 0.01% by mass maximum (Example E4).

例Ｅ１〜例Ｅ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、上記参考例Ｅにおける接合強度の値を考慮すると、例Ｅ１〜例Ｅ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）におけるＴｉＯ2膜（酸化物膜２０）とＭｏ支持基板（支持基板１０）との接合強度およびＴｉＯ2膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度は、それぞれ、１．５４および０．７８（例Ｅ１）、１．５４および１．００（例Ｅ２）、１．２１および０．７８（例Ｅ３）、１．５４および０．７８（例Ｅ４）と、いずれも高くなった。結果を表１０に示した。 Regarding the GaN composite substrates of Examples E1 to E4 (Group III nitride composite substrate 1), considering the bonding strength values in Reference Example E above, the GaN composite substrates of Examples E1 to E4 (Group III nitride composite substrate 1) The bonding strength between the TiO 2 film (oxide film 20) and the Mo support substrate (support substrate 10) and the bonding strength between the TiO 2 film (oxide film 20) and the GaN layer (group III nitride layer 30a) in FIG. 1.54 and 0.78 (Example E1), 1.54 and 1.00 (Example E2), 1.21 and 0.78 (Example E3), 1.54 and 0.78 (Example E4), respectively. Both were high. The results are shown in Table 10.

また、例Ｅ１〜例Ｅ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向の比抵抗（電気抵抗率）は、例Ｅ１が１．７×１０1Ωｃｍ、例Ｅ２が５．３×１０6Ωｃｍ、例Ｅ３が３．９×１０-2Ωｃｍ、例Ｅ４が５．２×１０0Ωｃｍあり、例Ｅ２以外は高い導電性を示した。結果を表１０に示した。例Ｅ２のＧａＮ複合基板は、ＴｉＯ2膜（酸化物膜２０）のＧａＮ層（ＩＩＩ族窒化物層３０ａ）側の主面におけるＮｂ（不純物）の濃度が０質量％であったため、膜厚方向の導電性が極めて低くなったものと考えられる。また、例Ｅ３のＧａＮ複合基板は、比抵抗が最も小さくなった。これは、ＴｉＯ2膜（酸化物膜２０）のＮｂ濃度が１０〜０．０１質量％でありＴｉＯ2膜全体としてのＮｂ濃度が高かったためと考えられる。 The specific resistance (electrical resistivity) in the film thickness maintaining direction of the GaN composite substrates (Group III nitride composite substrate 1) of Examples E1 to E4 is 1.7 × 10 1 Ωcm in Example E1 and 5. 3 × 10 6 Ωcm, Example E3 was 3.9 × 10 −2 Ωcm, and Example E4 was 5.2 × 10 0 Ωcm. Except for Example E2, high conductivity was exhibited. The results are shown in Table 10. In the GaN composite substrate of Example E2, the concentration of Nb (impurities) on the main surface of the TiO 2 film (oxide film 20) on the GaN layer (Group III nitride layer 30a) side was 0% by mass. It is considered that the electrical conductivity of the film was extremely low. The specific resistance of the GaN composite substrate of Example E3 was the smallest. This is presumably because the Nb concentration of the TiO 2 film (oxide film 20) was 10 to 0.01% by mass and the Nb concentration of the entire TiO 2 film was high.

Figure 2013084900
Figure 2013084900

（参考例Ｆ）
図１を参照して、多結晶で形成される直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＭｏ支持基板（支持基板１０）、直径２インチ（５０．８ｍｍ）で厚さが６００ｎｍのＳｒＴｉＯ3膜（酸化物膜２０）および単結晶で形成される直径２インチ（５０．８ｍｍ）で厚さが３００ｎｍのＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、ＳｒＴｉＯ3膜（酸化物膜２０）中のＬａ（不純物）の濃度と、ＳｒＴｉＯ3膜（酸化物膜２０）とＭｏ支持基板（支持基板１０）との接合強度との関係、ならびに、ＳｒＴｉＯ3膜（酸化物膜２０）中のＬａ（不純物）の濃度と、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度との関係を、以下のようにして調べた。 (Reference Example F)
Referring to FIG. 1, a Mo support substrate (support substrate 10) having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm and SrTiO 2 having a diameter of 2 inches (50.8 mm) and a thickness of 600 nm are formed of polycrystal 3 films (oxide film 20) and a GaN composite substrate (III nitride layer 30a) having a diameter of 2 inches (50.8 mm) and a thickness of 300 nm formed of a single crystal are joined in this order (III bonding strength of the nitride composite substrate 1), and the concentration of the SrTiO 3 film (oxide film 20) in the La (impurities), and the Mo support substrate SrTiO 3 film (oxide film 20) (supporting substrate 10) relationship, between the well and the bonding strength and density of the SrTiO 3 film (oxide film 20) in the La (impurities), SrTiO 3 film (oxide film 20) and the GaN layer and the (III-nitride layer 30a) The relationship below It was examined Te Unishi.

１．酸化物膜中の不純物の濃度と、酸化物膜と支持基板との接合強度と、の関係
支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＭｏ支持基板を用いたこと以外は、参考例Ｂと同様にして、５種類の積層基板１Ｓについてサンプルを作製し、引張試験によりそれらのサンプルの接合強度を測定した。いずれの積層基板１Ｓのいずれのサンプルも、Ｍｏ支持基板（支持基板）とＴｉＯ2膜（酸化物膜）との界面または界面の近傍で破断した。 1. Relationship between impurity concentration in oxide film and bonding strength between oxide film and supporting substrate Except that a Mo supporting substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm was used as the supporting substrate 10. In the same manner as in Reference Example B, samples were prepared for five types of laminated substrates 1S, and the bonding strength of these samples was measured by a tensile test. Any sample of any laminated substrate 1S was broken at or near the interface between the Mo support substrate (support substrate) and the TiO 2 film (oxide film).

各種積層基板１Ｓの接合強度は、Ｌａ（不純物）の濃度が０質量％のとき１．００、Ｌａ（不純物）の濃度が０．０１質量％のとき１．１１、Ｌａ（不純物）の濃度が０．１質量％のとき１．１４、Ｌａ（不純物）の濃度が１質量％のとき１．５７、Ｌａ（不純物）の濃度が１０質量％のとき１．２３であった。すなわち、Ｌａ（不純物）の濃度が０質量％のときに比べて、Ｌａ（不純物）の濃度が０．０１質量％〜１０質量％のときは、ＳｒＴｉＯ3膜（酸化物膜）とＭｏ支持基板（支持基板）との間の接合強度が高くなった。結果を表１１にまとめた。 The bonding strength of various laminated substrates 1S is 1.00 when the concentration of La (impurity) is 0% by mass, 1.11 when the concentration of La (impurity) is 0.01% by mass, and the concentration of La (impurity) is It was 1.14 when the concentration was 0.1% by mass, 1.57 when the concentration of La (impurity) was 1% by mass, and 1.23 when the concentration of La (impurity) was 10% by mass. That is, when the concentration of La (impurity) is 0.01% by mass to 10% by mass compared to when the concentration of La (impurity) is 0% by mass, the SrTiO 3 film (oxide film) and the Mo support substrate The bonding strength with the (support substrate) was increased. The results are summarized in Table 11.

２．酸化物膜中の不純物の濃度と、酸化物膜とＩＩＩ族窒化物層との接合強度と、の関係
参考例Ｂにおけるサンプルの接合強度の測定から、各種積層基板１Ｔの接合強度は、Ｌａ（不純物）の濃度が０質量％のとき１．００、Ｌａ（不純物）の濃度が０．０１質量％のとき０．７６、Ｌａ（不純物）の濃度が０．１質量％のとき０．７１、Ｌａ（不純物）の濃度が１質量％のとき０．５５、Ｌａ（不純物）の濃度が１０質量％のとき０．５４であった。すなわち、Ｌａ（不純物）の濃度が０質量％のときに比べて、Ｌａ（不純物）の濃度が０．０１質量％から１０質量％と高くなる程、ＳｒＴｉＯ3膜（酸化物膜）とＧａＮ層（ＩＩＩ族窒化物層）との間の接合強度が低くなった。結果を表１１にまとめた。 2. Relationship between the concentration of impurities in the oxide film and the bonding strength between the oxide film and the group III nitride layer From the measurement of the bonding strength of the sample in Reference Example B, the bonding strength of the various laminated substrates 1T is La ( 1.00 when the concentration of (impurity) is 0% by mass, 0.76 when the concentration of La (impurity) is 0.01% by mass, 0.71 when the concentration of La (impurity) is 0.1% by mass, It was 0.55 when the concentration of La (impurity) was 1% by mass, and 0.54 when the concentration of La (impurity) was 10% by mass. That is, the SrTiO 3 film (oxide film) and the GaN layer increase as the concentration of La (impurity) increases from 0.01% by mass to 10% by mass compared to when the concentration of La (impurity) is 0% by mass. The bonding strength with the (Group III nitride layer) was low. The results are summarized in Table 11.

Figure 2013084900
Figure 2013084900

図１および表１１を参照して、Ｍｏ支持基板（支持基板１０）、ＳｒＴｉＯ3膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）において、ＳｒＴｉＯ3膜（酸化物膜２０）とＭｏ支持基板（支持基板１０）との接合強度を高めるにはＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）濃度を高くすることが有効であり（特に、不純物濃度を１質量％程度とするのが好ましく）、ＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度を高めるにはＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）濃度を低くすることが有効であることがわかった。 Referring to FIG. 1 and Table 11, a GaN composite substrate (III) in which a Mo support substrate (support substrate 10), a SrTiO 3 film (oxide film 20), and a GaN layer (Group III nitride layer 30a) are joined in this order. In the group nitride composite substrate 1), the La (impurity) concentration of the SrTiO 3 film (oxide film 20) is increased in order to increase the bonding strength between the SrTiO 3 film (oxide film 20) and the Mo support substrate (support substrate 10). Is effective (in particular, the impurity concentration is preferably about 1% by mass), and the bonding strength between the SrTiO 3 film (oxide film 20) and the GaN layer (group III nitride layer 30a) is increased. It has been found that it is effective to lower the La (impurity) concentration of the SrTiO 3 film (oxide film 20) in order to increase it.

（実施例Ｆ）
図１および図２を参照して、支持基板１０として直径２インチ（５０．８ｍｍ）で厚さ５００μｍのＭｏ支持基板を用いたこと以外は、実施例Ｂと同様にして、例Ｆ１〜例Ｆ４として、Ｍｏ支持基板（支持基板１０）上にＳｒＴｉＯ3膜（酸化物膜２０）およびＧａＮ層（ＩＩＩ族窒化物層３０ａ）がこの順に接合されたＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）を作製した。 (Example F)
1 and 2, Examples F1 to F4 are the same as Example B except that a Mo support substrate having a diameter of 2 inches (50.8 mm) and a thickness of 500 μm is used as the support substrate 10. GaN composite substrate (Group III nitride composite substrate 1) in which a SrTiO 3 film (oxide film 20) and a GaN layer (Group III nitride layer 30a) are joined in this order on a Mo support substrate (support substrate 10) Was made.

例Ｆ１〜例Ｆ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）は、ＳｒＴｉＯ3膜（酸化物膜２０）のＬａ（不純物）の濃度が、ＳｒＴｉＯ3膜（酸化物膜２０）の支持基板１０側の第１主面２０ｓからＩＩＩ族窒化物層３０ａ側の第２主面２０ｔにかけて膜厚方向に、１質量％から０．０１質量％まで単調に変化し（例Ｆ１）、１質量％から０質量％まで単調に変化し（例Ｆ２）、１０質量％から０．０１質量％まで単調に変化し（例Ｆ３）、１質量％から１０質量％を経て０．０１質量％まで極大値を有するように変化していた（例Ｆ４）。 Example GaN composite substrate F1~ Example F4 (III-nitride composite substrate 1), the concentration of La (impurities) of SrTiO 3 film (oxide film 20), the supporting substrate of SrTiO 3 film (oxide film 20) It changes monotonically from 1% by mass to 0.01% by mass in the film thickness direction from the first main surface 20s on the 10 side to the second main surface 20t on the side of the group III nitride layer 30a (Example F1), 1% by mass. 1% to 0% by mass (Example F2), 10% to 0.01% by mass monotonically (Example F3), 1% to 10% by mass and 0.01% by mass maximum (Example F4).

例Ｆ１〜例Ｆ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）について、上記参考例Ｆにおける接合強度の値を考慮すると、例Ｆ１〜例Ｆ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）におけるＳｒＴｉＯ3膜（酸化物膜２０）とＭｏ支持基板（支持基板１０）との接合強度およびＳｒＴｉＯ3膜（酸化物膜２０）とＧａＮ層（ＩＩＩ族窒化物層３０ａ）との接合強度は、それぞれ、１．５７および０．７６（例Ｆ１）、１．５７および１．００（例Ｆ２）、１．２３および０．７６（例Ｆ３）、１．５７および０．７６（例Ｆ４）と、いずれも高くなった。結果を表１２に示した。 Regarding the GaN composite substrates of Examples F1 to F4 (Group III nitride composite substrate 1), considering the bonding strength values in Reference Example F above, the GaN composite substrates of Examples F1 to F4 (Group III nitride composite substrate 1) The bonding strength between the SrTiO 3 film (oxide film 20) and the Mo support substrate (support substrate 10) and the bonding strength between the SrTiO 3 film (oxide film 20) and the GaN layer (Group III nitride layer 30a) in FIG. 1.57 and 0.76 (Example F1), 1.57 and 1.00 (Example F2), 1.23 and 0.76 (Example F3), 1.57 and 0.76 (Example F4), respectively. Both were high. The results are shown in Table 12.

また、例Ｆ１〜例Ｆ４のＧａＮ複合基板（ＩＩＩ族窒化物複合基板１）の膜厚保方向の比抵抗（電気抵抗率）は、例Ｆ１が５．５×１０1Ωｃｍ、例Ｆ２が２．８×１０7Ωｃｍ、例Ｆ３が７．８×１０-2Ωｃｍ、例Ｆ４が２．１×１０1Ωｃｍであり、例Ｆ２以外は高い導電性を示した。結果を表１２に示した。例Ｆ２のＧａＮ複合基板は、ＳｒＴｉＯ3膜（酸化物膜２０）のＧａＮ層（ＩＩＩ族窒化物層３０ａ）側の主面におけるＬａ（不純物）の濃度が０質量％であったため、膜厚方向の導電性が極めて低くなったものと考えられる。また、例Ｆ３のＧａＮ複合基板は、比抵抗が最も小さくなった。これは、ＳｒＴｉＯ3膜（酸化物膜２０）のＬａ濃度が１０〜０．０１質量％でありＳｒＴｉＯ3膜全体としてのＬａ濃度が高かったためと考えられる。 The specific resistance (electrical resistivity) in the film thickness maintaining direction of the GaN composite substrates (Group III nitride composite substrate 1) of Examples F1 to F4 is 5.5 × 10 1 Ωcm in Example F1, and 2. 8 × 10 7 Ωcm, Example F3 was 7.8 × 10 −2 Ωcm, and Example F4 was 2.1 × 10 1 Ωcm. Except for Example F2, high conductivity was exhibited. The results are shown in Table 12. In the GaN composite substrate of Example F2, the La (impurity) concentration on the main surface of the SrTiO 3 film (oxide film 20) on the GaN layer (Group III nitride layer 30a) side was 0% by mass. It is considered that the electrical conductivity of the film was extremely low. In addition, the specific resistance of the GaN composite substrate of Example F3 was the smallest. This is presumably because the La concentration of the SrTiO 3 film (oxide film 20) was 10 to 0.01% by mass and the La concentration of the entire SrTiO 3 film was high.

Figure 2013084900
Figure 2013084900

今回開示された実施の形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。   It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

１ ＩＩＩ族窒化物複合基板、１Ｓ，１Ｔ 積層基板、１０ 支持基板、１０ｍ，３０ｎ 主面、２０，２０ａ，２０ｂ 中間膜、２０ｓ 第１主面、２０ｔ 第２主面、３０ ＩＩＩ族窒化物基板、３０ａ ＩＩＩ族窒化物層、３０ｂ 残りのＩＩＩ族窒化物基板、３０ｉ イオン注入領域、１００ サファイア支持基板。   1 Group III nitride composite substrate, 1S, 1T laminated substrate, 10 support substrate, 10m, 30n main surface, 20, 20a, 20b intermediate film, 20s first main surface, 20t second main surface, 30 Group III nitride substrate 30a group III nitride layer, 30b remaining group III nitride substrate, 30i ion implantation region, 100 sapphire support substrate.

Claims (4)

支持基板と、前記支持基板上に配置されている酸化物膜と、前記酸化物膜上に配置されているＩＩＩ族窒化物層と、を含み、
前記支持基板は多結晶で形成され、
前記ＩＩＩ族窒化物層は少なくともｃ軸方向に配向しているＩＩＩ族窒化物結晶で形成され、
前記酸化物膜は不純物が添加され、前記不純物の濃度は、前記酸化物膜において前記支持基板側の第１主面から前記ＩＩＩ族窒化物層側の第２主面にかけて膜厚方向で変化し、前記第１主面における前記不純物の濃度は前記第２主面における前記不純物の濃度よりも高い、ＩＩＩ族窒化物複合基板。 A support substrate, an oxide film disposed on the support substrate, and a group III nitride layer disposed on the oxide film,
The support substrate is formed of polycrystal,
The group III nitride layer is formed of group III nitride crystals oriented at least in the c-axis direction,
Impurities are added to the oxide film, and the concentration of the impurities varies in the film thickness direction from the first main surface on the support substrate side to the second main surface on the group III nitride layer side in the oxide film. The group III nitride composite substrate, wherein the impurity concentration in the first main surface is higher than the impurity concentration in the second main surface. 前記酸化物膜は、前記第１主面における前記不純物の濃度が１０質量％以下であり、前記第２主面における前記不純物の濃度が０．０１質量％以上である請求項１に記載のＩＩＩ族窒化物複合基板。   3. The III of claim 1, wherein the oxide film has a concentration of the impurity on the first main surface of 10% by mass or less and a concentration of the impurity on the second main surface of 0.01% by mass or more. Group nitride composite substrate. 前記酸化物膜の前記不純物の濃度は、前記酸化物膜において前記第１主面から前記第２主面にかけて膜厚方向で単調に変化する請求項１または請求項２に記載のＩＩＩ族窒化物複合基板。   3. The group III nitride according to claim 1, wherein the impurity concentration of the oxide film monotonously changes in the film thickness direction from the first main surface to the second main surface in the oxide film. Composite board. 前記支持基板は、窒化物、酸化物および金属からなる群から選ばれる少なくとも１種類を含む請求項１から請求項３のいずれかに記載のＩＩＩ族窒化物複合基板。   The group III nitride composite substrate according to any one of claims 1 to 3, wherein the support substrate includes at least one selected from the group consisting of nitride, oxide, and metal.
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